Metering Pump Technology Bulletin 210 The Metering Pump...... 1 Metering Pump Basic Components...... 1 Metering Pump Characteristics...... 2 Capacity and Pressure Capabilities Chart ...... 3 Liquid End Designs ...... 4 Packed Plunger ...... 4 Disc Diaphragm ...... 5 Mechanically Actuated Diaphragm...... 6 Metallic Diaphragm and Critical Service Head . . . 7 High Performance Diaphragm - Advanced Liquid End Design...... 8 Metering Pump Drive Mechanisms ...... 10 Hydraulic Bypass ...... 10 Polar Crank ...... 11 CENTRAC ...... 12 Capacity Adjustment ...... 14 Modifications ...... 15 Metering Pump System Components ...... 16 Other Milton Roy Products ...... 18 The Metering Pump he metering pump is a positive displacement chemical dosing device with the ability to vary capacity manually or automatically as process conditions require. It features a high level of repetitive accuracy and is capable of pump- Ting a wide range of chemicals including acids, bases, corrosives or viscous liquids and slurries. The pumping action is developed by a reciprocating piston which is either in direct contact with the process fluid, or is shielded from the fluid by a diaphragm. Diaphragms are actuated by hydraulic fluid between the piston and the diaphragm. Metering pumps are generally used in applications where one or more of the following conditions exist.

• Low flow rates in ml/hr or GPH • High accuracy feed rate is • Corrosive, hazardous, or high are required demanded temperature fluids are handled • High system pressure exists • Dosing is controlled by computer, • Viscous fluids or slurries need to microprocessor, DCS, PLC, or be pumped flow proportioning Metering Pump Basic Components Driver: Driver Mechanism: Flow Adjustment: The pump is usually driven by an The drive mechanism translates Pump flow rate is adjustable by AC constant speed motor. Variable the rotary motion of the driver into varying stroke length, effective speed, pneumatic, reciprocating stroke length, or stroking speed. and hydraulic drivers movement. Most metering are also utilized. Industrial duty pumps are pumps will supplied with Liquid End: submerge this a micrometer The liquid end design and materi- portion of the screw adjustment als of construction are determined pump in an similar to the by the service conditions, and the oil bath to assure reliability during one shown here. The micrometer nature of the continuous operation. can also be replaced by an elec- fluid to be tronic or pneumatic actuator to adjust pump flow rate in response handled. Driver Temperature, to process signal. flow rate, fluid viscosity, cor- Drive Mechanism rosiveness and other factors are considered.

Liquid End

Flow Adjustment

1 Metering Pump Characteristics

One Complete Cycle

1.The pumping action is developed Discharge by a reciprocating piston. This recip- rocating motion develops a flow Peak Flow- easily represented by a sine wave. ª’ªx Average Flow Actual flow rate is determined by Average the following formula: Flow Time Flow rate = Displacement x Cycles per unit of time.

Suction

Metering Pump

2.Unlike centrifugal pumps, flow rate is not greatly affected by Flow Q Centrifugal Pump changes in discharge pressure.

Pressure P

3.The metering pump flow vs. stroke character- istic curve is linear. It is not, however, necessar- ily proportional in that 50% stroke setting may not equal 50% flow. This is due to the fact that the calibration line may not pass through 0 on both axes simultaneously. By measuring flow at 2 stroke settings, plotting both points and drawing a straight line through them, other flow rates vs. Point 1 stroke can be accurately predicted. Q1, S1 The steady state accuracy of a correctly installed industrial grade metering pump is generally + 1.0% or better. Flow Although a metering pump can generally be Rate adjusted to pump at any flow rate between 0 and Q its maximum capacity, its accuracy is measured over a range determined by the pump's turndown ratio. Most metering pumps have a turndown Point 2 ratio of 10:1, which simply means that the pump Q2, S2 is within its accuracy rating anywhere between 10% and 100% of capacity. Centrac is an example of a new generation metering pump that features 0 50 100 higher accuracy, and a greater turndown ratio of % Setting “S” Stroke Length or Driver Speed 100:1. Therefore, this design will accurately dose anywhere between 1% and 100% of capacity.

2 Capacity and Pressure Capabilities

Capacity Per Head–GPH 0 5 10 20 30 40 50 75 100 150 200 350 500 750 1000 1500 2000 3000

mRoy XT & XW mRoy XT mRoy XW The maximum capacity of each Maximum Pressure Maximum– Maximum– 24” 1800-3000 psi 1.6 GPH (6 LH) 6.7 GPH (25 LH) pump is determined by gear ratio, Maximum No. Heads Minimum– Minimum– piston diameter, and motor RPM. mRoy XT mRoy 2 XW mRoy 0.4 GPH (1.5 LH) 2.8 GPH (9.8 LH) Maximum pressure rating applies to smaller piston diameters in each model. As the piston diameter and Centrac S Centrac S stroking speed increase, pressure Maximum Pressure Maximum– 23” 9000 psi 39.7 GPH (150 LH) capability decreases. See specific Maximum No. Heads Minimum– product data sheet for actual pres- 2 4.0 GPH (15 LH) sure rating at desired flow rate. Capacities shown are for simplex pumps. For those pumps that can Milroyal D Milroyal D be supplied with more than one Maximum– Maximum Pressure head, multiply the capacity by the 8” 3000 psi 53 GPH (200 LH) Maximum No. Heads Minimum– number of heads to determine 0.0081 GPH (0.0307 LH) 6 total capacity.

mRoy A & B mRoy A mRoy B Maximum Pressure Maximum– Maximum– 13”-24” 350-1500 psi 30 GPH (114 LH) 85 GPH (322 LH) Maximum No. Heads Minimum– Minimum– 2 0.065 GPH (.246 LH) 0.475 GPH (1.79 LH)

maxRoy B maxRoy B Maximum Pressure Maximum– 27” 150 psi 227 GPH (859 LH) Maximum No. Heads Minimum– 1 13.5 GPH (51.1 LH )

MacRoy G & D MacRoy 121/ ”- 271/ ” Maximum Pressure Maximum– 4 2 175 psi 300 GPH (1135 LH) Maximum No. Heads Minimum– 1 0.018 GPH (0.068 LH)

Milroyal B Milroyal B Maximum Pressure Maximum– 11” 7500 psi 500 GPH (1893 LH) Maximum No. Heads Minimum– 0.11 GPH (42 LH) 8

Centrac B Centrac B 25” Maximum Pressure Maximum– 1575 psi 550 GPH (2082 LH) Maximum No. Heads Minimum– 2 0.45 GPH (100:1 Turndown)

Milroyal C Milroyal C Maximum Pressure Maximum– 18” 7500 psi 2510 GPH (9500 LH) Maximum No. Heads Minimum– 5 0.43 GPH (1.628 LH)

PrimeRoyal PrimeRoyal Maximum Pressure Maximum– 72” 30,000 psi 2510 GPH (9500 LH) Maximum No. Heads Minimum– 3 0.43 GPH (1.628 LH)

3 Liquid End Designs he liquid end, which is tures in common. First, the liquid the suction ball check from its seat referred to as the wetted is drawn into the wetted end by allowing liquid into the pump. At Tpart of the pump, is selected the rearward motion of a pis- the same time, the piston's motion to meet the specific service condi- ton, and expelled by the forward and system back pressure hold the tions of the application. Required motion. To achieve this, the meter- upper check valve (discharge) closed. flow and pressure ratings are con- ing pump is supplied with check This is then reversed during the sidered, as well as the physical and valves at the suction and discharge discharge stroke. chemical properties of the liquid. connection points. The check Check valves are available in sev- The liquid end's ability to protect valves contain and release the eral different designs and configura- the environment is also a major chemical based on system condi- tions. The choice of ball or poppet consideration when dealing with tions and gravity. style is determined by Milton Roy's toxic or hazardous chemicals. During the suction portion of the Engineering department based on All liquid ends have several fea- stroke, the motion of the piston lifts capacity of the specific pump. Discharge Ball Check Valve Ball Check Seat

Single Double Poppet Ball Ball Style Discharge Check Check Check Piston Valve Valve Valve Suction Most pumps feature either single or double ball configuration as standard. The user can also select single or double ball when the application is better served Process Fluid by one or the other. For example, slurries or liquids with large fibers or particles can cause a single ball to leak if particles are trapped between the ball and seat. Suction Ball Therefore, a double ball check offers more stability and accuracy. On the other Check Valve hand, since each check valve causes some resistance in the flow path even when open, viscous fluids are better handled with a single ball suction check valve. Packed Plunger The packed plunger style liquid end is the only Discharge Ball liquid end in which the piston is in direct contact Check Valve with the process fluid. This direct contact offers a number of advantages, including: high suction Grease Fitting and discharge pressure capabilities; high temper- ature resistance, and lowest NPSH requirements. The reciprocating piston requires packing to seal the wetted parts from the atmosphere. This simple design is effective, but places limitations on the use of packed plunger pumps in certain Piston applications. Because a small amount of controlled leakage past the packing must be expected, this style liquid end should not be used with hazardous or toxic chemicals. Additionally, the friction between Packing Lantern Ring the piston and the packing results in wear that increases leakage. Periodic packing adjustment Process is necessary to maintain volumetric efficiency. To Suction Ball Fluid avoid problems associated with leakage, consider Check Valve a diaphragm style liquid end. Available on: Milroyal B, Milroyal C, Milroyal D, Centrac, and The packed plunger can handle pressures up Maxroyal. o to 15,000 psi, and temperatures to 600 F (with Standard Materials of Construction: 316 SS, Alloy 20, Cast Steel special modifications). (larger models)

4 Disc Diaphragm The disc diaphragm liquid end The hydraulic and process fluids ered redundant since this design is has a teflon diaphragm which acts pass through carefully engineered extremely durable. as a barrier between the piston holes in the contour plates in order Because the process fluid must and the process fluid. The piston's to come into contact with the pass through relatively small holes pumping motion is applied to diaphragm. Relief and refill valves in the contour plate, the disc dia- hydraulic fluid which causes the control the volume of hydraulic phragm liquid end is not the best diaphragm to flex back and forth fluid. An automatic air bleed valve choice for slurries. With the excep- as the piston reciprocates. continuously purges air from the tion of the mRoy P design, disc The hydraulically actuated dia- hydraulic fluid. diaphragms are usually not the best phragm operates with equal pres- The diaphragm style pump is choice when pumping viscous fluids. sure between the hydraulic and sealed. It therefore is an excel- The disc diaphragm is capable of process fluids. This eliminates dia- lent choice for hazardous, toxic, handling fluids where the required phragm stress, since the pressure or corrosive chemicals. For extra injection pressure is 3500psi or is essentially equal on both sides at protection, double diaphragm and greater and the fluid temperature all times. Two contour plates encase leak detection modifications are exceeds 250oF. the diaphragm to contain its travel. available, although they are consid-

Discharge Ball Automatic Check Valve Air-Bleed Valve

Relief Valve

Contour Plates Teflon Diaphragm Piston Process Fluid

Hydraulic Fluid

Reservoir Suction Ball Hydraulic Check Valve Fluid

Available on: mRoy A, mRoy B, Milroyal B, Milroyal C Standard Materials of Construction: 316 SS, Alloy 20, Plastic

5 Liquid End Designs Mechanically Actuated Diaphragm Design he Milton Roy Family of mechanically-actuated diaphragm pump is called the MacRoy Series G. They represent the best balance between low pump cost and high quality performance. Because it has zero Tdiaphragm leakage, it makes a great pump for critical and otherwise expensive chemicals or where envi- ronmental issues are involved. The mechanically-actuated series is an excellent choice where slurries and abrasive chemicals are required up to the pump's maximum flow and pressure ranges. They are also well tolerant of high viscosity liquids providing an economical solution for a variety of difficult applications. Mechanically-actuated pumps are only limited to flow as a experienced by a liquid having off- operate with a plunger directly matter of wetted end volume. gas characteristics. Some of these attached to the diaphragm. This Maximum life of the pump can liquids that can generate off-gases attachment generally takes place be achieved by replacing the as a result of pressure losses are from a bolt and clamp being diaphragm at the recommended NaOCl, H2O2, and some specialty placed through the plunger and service interval. Leak detection chemicals. Mechanically-actuated through the diaphragm. The direct can be easily found from the pumps work well in these applica- attachment of the piston to the air-filled chamber residing gener- tions providing 10:1 turndown as diaphragm connects the pump's ally at atmospheric pressure on a standard across the product line. drive and motor to the liquid end. the drive side of the liquid end. The addition of VFD technology The motion of the pump drive This provides the least expen- and remote stroke control will moves the plunger back and forth, sive leak detection option in bring the turndown as high thereby causing suction from the the marketplace. as 100:1. supply tank and pumping the fluid As with any chemical where gas Mechanically-actuated diaphragm of choice through the attached binding can be a problem, it is rec- pumps are easily maintained conveyance infrastructure. This ommended that a degassing valve and provide years of service for series of pumps generally find be used to release off-gases from little effort. pressure peaks at 175 PSI, but the agitation or pressure changes

Check Valve Assembly

Oil Seal

Diaphragm Assembly

Slotted Pan Diaphragm Cap Head Screw

Diaphragm Head Diaphragm Assembly

Process Fluid Set Screw

Check Valve Hydraulic Assembly Fluid

Available on: MacRoy, Standard Materials of Construction: 316 SS, Alloy 20, Plastic

6 Metallic Diaphragm Liquid End and Critical Service Head he Milton Roy Series of Metallic Diaphragms are unparalleled for use in critical, high pressure appli- cations such as oil and gas platforms and specialty industrial applications. They are especially useful Twhere temperatures and pressures of both the environment and the process chemical can be vari- able or otherwise difficult. The Metallic diaphragm lines are preferred for their longevity and durability in many difficult applications.

Metallic diaphragm metering traditional materials. The metal diaphragms because of their high pumps are hydraulically-actuated design of the diaphragm also man- reliability and longevity. In any appli- in the same manner and style as a ages difficult chemicals such as cation where critical service is standard hydraulically-actuated drive abrasives, slurries and other special required, the Milton Roy Metallic liquid end. However, the teflon or requirements compounds easier Diaphragm is the product of choice other usual diaphragm material is and more efficiently than its more for these chemical dosing situations. replaced with a special metal alloy standard version. particular to the application to Many oil and gas offshore drill- produce higher pressures than more ing platforms require metallic

O-Ring

Screws Diaphragm Diaphragm Head Backup O-Ring Suction Ball Displacement O-Ring Check Valve Chamber O-Ring Backup O-Ring Detail B Diaphragm Head Bolts /Nuts

Set Screws Plunger Sleeve

Plunger

Plunger Adapter Nut

Process Fluid

Hydraulic Fluid

Available on: Milroyal C and PrimeRoyal: 316 SS, Alloy 20, Plastic 7 High Performance Diaphragm... he High Performance Diaphragm liquid end, HPD, combines all of the best characteristics of traditional liquid ends into one technologically advanced design. Its operating characteristics and simplicity of opera- Ttion make it the best pump to consider first for most metering pump applications. HPD operation is similar to the disc diaphragm in that it is hydraulically actuated and utilizes the same shape and diaphragm. It is similar to a tubular diaphragm in the respect that the process fluid has a “straight through” path through the liquid end. Its low NPSH requirements are similar to that of a packed plunger liquid end. But the primary advantages of the HPD are the unique design features that separate it from tra- ditional designs. tour plate, required by traditional disc Discharge The MARS Advantage diaphragm liquid ends, places limita- A hydraulically actuated diaphragm Process Contour Plate liquid end design requires a refill tions on the types of process fluids Hydraulic Side system to compensate for hydraulic the pump can handle (such as slur- Contour Plate ries) since the process fluid must also fluid that bleeds past the piston or Hydraulic Fluid through an air bleed valve during nor- pass through contour plate holes. The mal operation. Hydraulic fluid is also process contour plate also creates a expelled from the chamber through pressure loss which raises the NPSH the internal relief valve when the sys- requirement of the liquid end. Piston tem experiences excess pressure, and therefore must also be replenished. The HPD features a Mechanically Process Diaphragm The MARS System Actuated Refill System (MARS) that Fluid The MARS System eliminates the offers a number of advantages over Suction need for a process contour plate by traditional refill systems. To under- Traditional Liquid End with Process assuring that the hydraulic fluid can stand the advantages of MARS, tra- and Hydraulic contour Plates (refill only be refilled when the diaphragm ditional refill systems must first be system not shown) has traveled all the way back to the explored. hydraulic contour plate. The dia- phragm presses against the MARS valve, which only then permits a pop- Traditional Designs pet valve to open from the vacuum Traditional designs use a system created by insufficient hydraulic fluid. that refills the chamber when a (See the illustration lower right) vacuum is created by the inability of Hydraulic overfill is therefore the diaphragm to move beyond the impossible. With the process con- hydraulic contour plate. It also refills tour plate gone, the straight through when the suction is momentarily or path of the process liquid makes the permanently starved by accidental HPD a perfect choice for slurries valve closure, insufficient NPSH, or and viscous materials. It also lowers other similar occurrences. When this the NPSH requirements of the pump, happens, the hydraulic fluid chamber is since pressure loss through a process overfilled because a vacuum has been contour plate is eliminated. created even though the diaphragm Typical Contour Plate(Section cutaway) The MARS system also simplifies has not been able to travel rearward. to come into contact with the dia- HPD start-up. Unlike other hydrau- To avoid diaphragm rupture due to phragm. The pattern and size of these lic liquid ends, the refill valve does overfilled hydraulic oil, a process side holes requires careful engineering to not need adjustment. Additionally, contour plate stops the diaphragm's maintain the contour plate strength since the HPD hydraulic fluid can- forward travel, and forces the hydrau- required to withstand the force of the not be overfilled, there is no need lic relief valve to open, thus expelling diaphragm experienced at operating to perform delicate procedures to the excess fluid. pressure. synchronize hydraulic fluid balances The contour plate is a concave The hydraulic contour plate does (a difficult task required for tubular (actually, concavo-convex) disc that not cause any problems in pump and other double diaphragm liquid supports the diaphragm and limits its operation since the hydraulic fluid ends). With the HPD, you just fill travel. The plate has a series of holes passes easily through the contour the reservoirs, and turn it on. bored through it to permit the fluid plate holes. However, a process con-

8 ...Advanced Liquid End Technology HPD Preshaped Composite Diaphragm

he HPD features a pre- Milroyal B shaped PTFE/elastomer HPD Low Flow Tcomposite disc diaphragm. On the process side, the chemi- cal resistance of PTFE is utilized. On the hydraulic side, the elasto- Full side view of HPD Liquid End on MilRoyal Drive mer imparts favorable elastic and mechanical factors. Air Bleed/Relief Valve The composite diaphragm elimi- Standard Materials: nates the inherent problems of 316SS. Alloy 20, Plastic. pure PTFE diaphragms. PTFE tends to cold flow when compressed between two metal parts (such as those required to seal the hydrau- lic side from the process side).

MARS Valve The HPD composite diaphragm Poppet features an integral "O" ring seal around the perimeter of the dia- phragm, which provides a better Mechanically Actuated Refill System (MARS) Piston seal between hydraulic and process fluids than conventional diaphragm Composite Diaphragm materials. The HPD is capable of handling pressures up to 3025 psi and tem- o Removable peratures up to 300 F (with spe- Check Valve cial modifications). Hydraulic Refill Line

PTFE Elastomer

Process Hydraulic Reservoir Hydraulic Fluid Fluid Fluid Preshaped Available on: Milroyal B, Milroyal C, Milroyal D, Centrac and Maxroyal. Composite Standard Materials of Construction: 316SS, Alloy 20, Plastic. Diaphragm. MARS System Operation

D D D

A C A C A C

B B B

Figure 1 Figure 2 Figure 3 Diaphragm (A) and piston (C) are Diaphragm (A) and piston (C) are full Diaphragm (A) and piston (C) are full full forward. Mars valve (B) in for- rearward. Mars valve (B) is also rear- rearward, once again forcing Mars valve ward position holds poppet valve (D) ward due to diaphragm position, thus (B) to its rearward position, which allows closed, preventing refill line hydraulic freeing poppet (D) to open if required. poppet (D) to open if required. Low oil oil from entering the chamber. Poppet (D) is shown closed, indicating volume creates a vacuum and opens pop- hydraulic oil refill is not required. pet, permitting hydraulic fluid to enter the chamber from the refill line.

9 Metering Pump Drive Mechanisms All Milton Roy drive mechanisms feature gears that are submerged in an oil bath to assure long life. Capacity can be adjusted while the pump is running or stopped, + 1.0% accuracy over a 10:1 turn-down ratio. Hydraulic By-Pass The hydraulic by-pass mechanism features a piston with a constant stroke length that pumps hydraulic fluid, thus transferring the pumping motion to a diaphragm. Therefore, this type of drive can only mate with a hydrauli- cally actuated diaphragm liquid end. Capacity is varied by changing the location of a hydraulic by-pass port over the piston's path of travel. If the port is positioned at 50% of the piston's stroke length, hydraulic fluid will be relieved through the port during the first half of the piston's stroke, and pumped against the diaphragm during the remaining half. This type of drive is often called "hydraulic lost motion," because a portion of the piston's travel does not transmit pumping energy when the capacity adjustment is less than 100%. Both the mRoy and the Maxroy are hydraulic by-pass style pumps. Both develop reciprocating piston motion by way of a worm gear set and eccentric.

By-Pass Control By-Pass Port mRoy A, mRoy B Motor Plunger In the mRoy, the piston pumps hydraulic fluid, which either forces Eccentric Control Discharge the diaphragm to flex, or is relieved Valve through the by-pass port. A control valve positions the port based on a desired capacity setting. The mRoy drive with its standard Diaphragm disc diaphragm liquid end features: • Simplex or Duplex liquid ends Stroke Length • Maximum capacities ranging Worm Gear Set between 0.43 GPH and 85 GPH The mRoy drive with (170 GPH Duplex) it’s standard disc dia- Reservoir Hydraulic Hydraulic Process Suction • Maximum pressures up to 1800 psi phragm liquid end. Fluid Fluid Fluid maxRoy B In the maxRoy, capacity is varied by positioning a stroke adjust sleeve over by-pass ports bored through the hollow piston. When operating at 100%, the ports are covered, which traps hydraulic fluid in the hydraulic pumping chamber. Once trapped, the piston's pumping action forces the hydraulic fluid to flex the diaphragm. A cup valve, which is attached to the diaphragm, closes all hydraulic paths to the diaphragm when it has reached the full forward position. This eliminates a process contour plate, as well as excessive hydraulic pressure on the diaphragm, since any excess hydraulic fluid in the hydraulic pumping chamber cannot reach the diaphragm, and is forced through the internal relief valve to the fluid reservoir. Discharge Capacity Adjustment Diaphragm By-Pass Ports The maxRoy drive features: • Maximum flow rates between 135 GPH and 227 GPH

Eccentric • Maximum discharge pressures of 150 psi The maxRoy is an excellent choice for mid-range metering pump capacity at low pressure. Its design is more economical than Hydraulic high pressure pumps in the same capacity Fluid range, without sacrificing ruggedness and Cup Valve Stroke Adjust accuracy. The "straight through" process fluid Sleeve Hydraulic Oil Piston Worm Reservoir Hydraulic path allows maxRoy to be applied to many of Suction in Pumping Chamber Gear Set Fluid the same services as the HPD liquid end.

10 Polar Crank he unique polar crank drive piston to the full forward position at between zero and maximum stroke is the heart of the Milroyal the end of the discharge stroke. As for extremely accurate controlled Tseries metering pump. It is the crank continues to rotate, the volume pump settings. considered the most advanced and angle of the crank causes the con- reliable variable stroke length drive necting rod to pull the crosshead The Milroyal polar crank drive available in high pressure/high flow and piston until it reaches the full features: industrial duty metering pumps. rearward position at which point • Maximum capacity ranges In the polar crank drive, a high the connecting rod has reached the between 0.033 GPH (125mL/hr.) speed worm gear reduces the RPM bottom of the rotation cycle. and 2510 GPH depending on supplied by the motor, and provides Regardless of the stroke length frame size, stroking speed, and the lower RPM to a rotating crank. A setting, the top of the rotation cycle plunger diameter connecting rod with spherical bear- always forces the crosshead and the • Discharge pressures up to ings on each end links the crank to piston to the full forward position 7500 psi the crosshead and piston assembly. at the end of each discharge stroke. The worm gear and crank assembly This assures complete scavenging • Up to 8 pumps multiplexed pivots in an arc about the worm shaft of the liquid end during each stroke and driven by one motor center to change stroke length. The cycle. • HPD, packed plunger, disc piston stroke length is determined by The angle of the polar crank can diaphragm, or tubular the angle of the assembly. be adjusted in infinite increments diaphragm liquid ends For example, when the pump is at zero stroke, the worm/crank assem- Lubricating Oil bly is in a vertical position. (Figure 1) Connecting Rod Relief Valve The crank then rotates in a vertical Worm Shaft plane and one end of the connecting rod revolves with it. The crosshead Cross Worm and the piston remain stationary Figure 1 Head Gear Micrometer Zero Stroke Rotating because no reciprocating action is Crank Capacity produced. When the pump is adjust- Control ed full stroke (or maximum capacity), Stroke the rotating crank is moved to its Length Worm Gear Rotating Crank maximum angle from the vertical axis. Discharge (Figure 2) At the top of the rotation Lubricating Oil cycle the connecting rod is pushed This illustration demonstrating the forward, moving the crosshead and Figure 2 Suction Full Stroke polar crank at full and zero strokes Pressurized Lubrication System To achieve a high thrust capac- tem. This positive oil pressure lubri- crosshead. During the suction (rear- ity and extend component life, the cation ensures long bearing life and ward) stroke the lubricant is trapped. Milroyal B and C polar crank drives permits the Milroyal pump to operate It is then forced through the cross- feature a pressurized lubrication sys- at very high suction and discharge head, into the crosshead connecting Lubricating Oil pressures. rod bearing, through the hollow con- Piston Relief Valve As the cross- necting rod, and finally to the crank head moves connecting rod bearing. By forcing the Worm Shaft forward during oil through this path, every moving the discharge part is lubricated during every com- Worm Gear stroke, oil from plete cycle of the pump. the reservoir To reduce the wear of moving parts is drawn up and extend oil life, a magnetic strainer through a ball cleans the oil before it enters the Lubricating Oil Crosshead Micrometer check into a pressurized system. Stroke Magnetic Strainer Connecting Rod Adjustment cavity in the

11 CENTRAC – The Automatic Process Advanced Drive Technology entrac represents a new result is a metering pump that boasts Centrac is different from tradi- concept in metering pump twice the accuracy over a turndown tional designs in many ways. The Cdrive design. It is the first ratio ten times greater than tradi- most significant way is the close true innovation in metering pump tional designs. relationship between the driver drives to be introduced in decades. Centrac's name clearly announces and drive mechanism and how they Centrac was developed by combin- its capabilities: enhance overall pump performance. ing the highest level of gear reduction CENT-100:1 turndown ratio To understand Centrac better, these design, and the latest technology in R-Response & Reliability two design elements and their inter- electronic variable speed drives. The AC - + 0.5% steady state accuracy dependence need to be explored. Centrac's Unique Gear Reduction System Centrac's impressive operating reciprocating motion, this gear set characteristics are the result of a runs quietly and efficiently with few unique constant stroke length drive moving parts. All moving parts are mechanism that depends on a spe- submerged in oil to ensure long life. cial electronic variable speed drive The graph below indicates the to vary pump flow rate. This offers greatest advantage of Centrac's a number of advantages. special gear design. The flat torque Traditional designs utilize worm curve (vs. the worm gear set) allows Operator Control Station gear sets to convert motor rotation Centrac to operate at or below to reciprocating motion through 1% of speed without placing extra Centrac's Advanced an eccentric or similar mechanism. demand on the motor, thus permit- Electronic Variable Worm gears are the best choice ting Centrac's 100:1 turndown ratio. when the drive mechanism is The simple drive mechanism also Speed Drive required to allows Centrac to be Conventional AC and DC variable incorpo- + easily duplexed within speed drives are limited to turn- rate a vari- Motor Drive Gear Low Speed the same housing down ratios between 5:1 and 30:1. able stroke (18 to 1800 RPM) Eccentric & Gear by adding a second This is insufficient to take advantage length piston and liquid end of the turndown capabilities of adjustment. Piston opposite the primary Centrac's gear design. They oper- + liquid end. Centrac's New technology in brushless DC ate well at capacity can therefore motors and controllers has created high rotary be doubled economi- advanced drives capable of strong speeds, due cally and efficiently. operation at low speeds. Centrac's Block transfers Rotating Eccentric to an oil Motion to Reciprocating Motion variable speed shield that CENTRAC Scotch drive delivers develops Yoke Drive rated torque between at less than 200 100:1 Turndown the gear surfaces. Unfortunately, they 10:1 Turndown 1% (100:1 lose that shield at lower speeds, turndown) 180 T y which causes wear and raises motor pi of maximum ca l o torque requirements. This limits 160 f W rated RPM or m G worm gears to a 10:1 turndown ear while main- Pump ratio. 140 Drives taining steady Centrac, on the other hand, uti- state speed lizes a special helical gear set. Since 120 control at bet- + there is no need for stroke length Typical of CENTRAC ter than adjustment, the gear set is very Required % of Motor Torque 100% 0.1%. It is the simple. Also, helical gears are known Full 0 10 20 50 100 175 200 1700 1800 perfect match Load for operating with low noise and Motor Speed-RPM for Centrac's low friction. Combined with a basic drive mecha- scotch yoke mechanism to develop Torque vs. Motor Speed-CENTRAC and Worm Gears nism.

12 Metering Pump

Motor Mount Crosshead Eccentric Cage Eccentric

Liquid End Mounting Optional Duplex Surface Configuration

Driver Shaft Gear Assembly Main Gear

Centrac's variable speed drive lic fluid volume remains constant. Centrac's features include: features: When the hydraulic balance is dis- • 100:1 turndown ratio turbed, as in variable stroke length • 100:1 turndown ratio • + 0.5% steady state accuracy designs, the full result of dosage • + 0.1% steady state speed changes can take minutes or hours. • Instant response to dosage control Centrac's instant response provides changes • smart commutation - permits smoother operation in closed loop • Simple but robust design for accurate feedback signal or automated systems. It also assures reliability • no brushes (low maintenance) proper dosage at all time in systems • Precise feedback signal requiring very close dosage tolerance. • constant torque at low speeds - • Efficient drive sizing permits efficient driver sizing • Mates with advanced HPD liquid Accuracy end for maximum performance + Centrac's 0.5% steady state • Capacity range between 0.45 100:1 Turndown Ratio accuracy over its full turndown The flexibility of a 100:1 turn- GPH minimum and 1100 GPH ratio is a result of the constant down ratio permits Centrac to maximum stroke length, and the precise speed be applied where a wide range of control of Centrac's drive. This level • Discharge pressures up to dosage rates are required. It also of accuracy provides maximum 1575 psi provides built-in growth potential chemical economy while assuring • Economical duplex configuration by pumping efficiently in systems stable automatic operation and opti- availability requiring a fraction of the pump's mum process quality. capacity for the short term dur- • Compact design higher capacity ing start-up or early phases of an in a small footprint expanding project. Centrac provides all this without compromising accu- Connection Diagram Motor Control Optional Remote racy or drive power. Operator Control Drive Motor Speed Response (Flow Rate) Centrac responds instantly to Output Signal changes in dosage rate. Its con- stant stroke length does not upset the balance within the liquid end AC Input Power Remote Speed (Flow Rate) hydraulic system, that is, hydrau- Control Signal

13 Capacity Adjustment etering pumps allow the user to vary capacity as the process requires. All Milton Roy metering pumps permit adjustment whether the pump is running or not. MWith the exception of the Centrac (see Centrac drive), Milton Roy pumps are supplied with a manual micrometer for performing manual capacity adjustments. Depending on the type of drive mechanism and the application requirements, one of several capacity adjustment options can be supplied. Manual Micrometer The manual micrometer can be used to adjust the metering pump's capacity anywhere between 0 and 100%. While not directly propor- tional to flow, this calibrated adjust- ment can be used to accurately set pump capacity based on the pump performance curve within + 1.0% Manual over the turndown ratio. Micrometer

Electronic Actuator Option Available for: mRoy A & B, MaxRoy, Milroyal B & C The Milton Roy Electronic Actuator responds to electronic process signals or remote manual adjust- ments. In addition, a local handwheel is provided to permit manual adjustments when unpowered. Milton Roy's electronic actuator is different from electric actuators in that it utilizes electronic limits. It is built around stepper motor technology, which allows it to travel precisely to position without overshoot or hunting. This design also provides superior operating characteristics such as: • 100% duty cycle • + 0.5% position accuracy or better • low maintenance Remote control stations are available for local/remote selection and manual capacity adjustment. Specifications: • NEMA 4 (Explosion proof available) • 1-5 VDC stroke position • 4-20 mA input signal output signal standard • Single phase 50/60 • Direct or reverse acting cycle 115 VAC Electronic Actuator on mRoy A

Pneumatic Actuators Option Available for: mRoy A & B, Milroyal B & C Automatic systems that supply a pneumatic process signal benefit from the Milton Roy pneumatic actuator. A separate air control panel is available for remote control and auto/ manual switching. Specifications: • 3-15 or 3-27 psi pneumatic signal • Direct or reverse acting • Requires 60 psi supply air pressure

Pneumatic Actuator

14 Modifications Double Diaphragm With Diaphragm Rupture Detection System Milton Roy's diaphragm liquid ends tion, the two diaphragms are pushed are, by design, leakproof and durable. tightly together and are separated In some applications, however, added only around their outside edge by assurance is desired to protect the the intermediate ring. The rupture pump from hostile chemicals, or detection system senses a pressure protect the process from contami- only when a diaphragm ruptures. The nation by hydraulic fluids. For these system is not affected by changes in situations, Milton Roy has developed pump discharge pressures. a highly reliable diaphragm rupture This system is available for metal- detection system. lic liquid end mRoys, maxRoys, and The system consists of two sepa- HPD's. A different design centered rate diaphragms, a hollow interme- around sensing changes in conductiv- diate ring, and a pressure gauge or ity is also available for a number of switch. During the normal opera- liquid ends.

Application Engineering: Custom Modifications Milton Roy offers a wide variety of standard pumps to satisfy most applications. In addition, our Applications Engineering department is capable of supplying specialty engineered products. Capabilities include: • Special liquid end materials including diaphragms, diaphragm heads, check valves, etc. • Special piston diameters • High temperature or pressure modifications • Unique multiplex arrangements • Application counseling • Special sensors, indications, or instrument interface • Special drive modifications or gear ratios

15 Metering Pump System Components Proper metering pump system operation depends upon the selection of appropriate system components. Milton Roy offers high quality accessories to suit your application requirements.

1.Safety Relief Valves 2.Back Pressure Valves 3.Pulsation Dampeners Most piping systems require the To prevent unmetered liquid from The metering pump's reciprocat- use of an external safety valve to free-flowing through the pump, ing motion provides a pulsating dis- protect the piping from over-pres- metering pump systems require a charge flow. Applications requiring a sure. Diaphragm pumps feature greater pressure in the discharge steady flow can eliminate over 90% internal safety valves to protect the line than the suction or inlet line. of the pulsations with a pulsation pump, but external safety valves are When the process does not supply dampener. Dampeners are available still recommended. Milton Roy pro- a minimum of 25 psi above the suc- for pressures to 1000 psi. Sizing is vides safety relief valves to match tion pressure, a back pressure valve based on cubic inch/stroke displace- the operating pressures of all pumps is required. Standard back pressure ment of the specific pump. we manufacture. Standard safety valves are available in specialty steel, relief valves are available in specialty 316 ss, alloy 20 and PVC . steel, 316 SS, alloy 20, and PVC.

4.Calibration Columns 5.Mixroy® Mixers 6.Tank Chemical All Milton Roy metering pumps Accurate dosing requires proper Feed Systems are factory tested. Once installed, mixing of the solution being Milton Roy offers tanks (in most ® mixers are direct pump calibration should be periodi- pumped. Mixroy available tank capacities) in steel, drive, high speed units designed for cally determined to verify proper stainless steel, and polyethylene. mixing medium and low viscosity operation, especially after the They are also available with pumps fluids and dispersion of light solids. performance of any maintenance. and mixers mounted, plumbed, and Milton Roy calibration columns ready for installation. provide an inexpensive means of assuring pumping accuracy.

16 Typical Installation

1 To Process Safety Valve 5 3 Pulsation Dampener 2 Ball Back 4 Valve Pressure Calibration 6 Valve Columns Tank

Ball Ball Valve Pump Valve Ball Valve

7 Strainer

Tank Cover

Pipe Wire Plug Screen Wire Fiberglass Screen

Balls Lower Housing

Bushing Pipe Plug

7.Strainers/SludgeTraps 8.Chemical Dosing 9.Instruments The metering pump's check valves Systems Milton Roy offers a full line of should be protected from particles Milton Roy offers the "RoyPak" water quality meters for use as a and debris by installing a strainer in family of chemical dosing pre- stand-alone or in conjunction with the suction line. engineered systems. The standard the RoyPak system. When pumping concentrated sulfu- RoyPak provides manual control Water quality - including PH, ric acid, a sludge trap is required to and all accessories to allow for ORP, chlorine residuals, DO (dis- trap sludge particles while providing proper operation. solved oxygen) - and other neces- easy cleaning or flushing. The RoyPak Setpoint paces the sary water quality measurements Foot valves and strainers are avail- dosing from your single input. are available. able for applications that pump fluid The RoyPak Setpoint Plus uses a from replaceable drums. "Y" type line of instruments to provide a strainers can also be supplied for in- full closed-loop solution. line protection in standard systems.

17 Other Milton Roy Products Streaming Current Detector ilton Roy's Streaming Current Detector M(SCD) is used to monitor and control coagulants in water or wastewater treatment. The SCD is an on-line instrument, therefore consistent effluent quality is assured. In addition to water and wastewater treat- ment, the SCD is widely used in paper making, petroleum, food, chemical, and other industries where close control of coagulant or charge altering chemicals are beneficial.

The Milton Roy Family of Streaming Current Detectors

Electronic Actuators A broad line of electronic actuators, similar to those used on Milton Roy pumps, is available for control valve actuation and other applications requiring precision and dependability. These advanced electronic actuators out- perform standard electric designs by utilizing stepper motor technology.

Milton Roy's electronic actuators offer the following advantages: • 100% duty cycle • Electronic limit switches • Direct to position operation-no hunting or overshoot • Rotary or linear designs • AC and DC units • Responds to 4-20 mA, split range, digital and other process signals • Maximum torque - 3800 in-lbs (317 ft-lbs) • Maximum thrust - 1100 lbs • Optional controllers and failsafe units

18 Notes Notes

BulletinBulletin 210210 RevisionRevision BB 12/0512/05