Guide to Regulators Index Section 1 page 4 Regulator Primer Section 2 page 10 Matheson’s Product Line Section 3 page 16 Regulator Options and Accessories Introduction Section 4 page 20 Choosing the right regulator Using Your for your application is critical – Regulator and often difficult. Product application, gas service, and Section 5 required delivery pressure all page 27 influence regulator selection. Performance At Matheson, we understand Evaluation and Troubleshooting gases, and we understand the importance of using the appropriate equipment for Section 6 each gas. Matheson’s Guide page 30 to Regulators is a valuable tool Glossary of that will help you pick the Regulator Terms right product for your application, and get the most reliable results. 2 3 Features Determine Function: Section 1 Regulator Primer What makes a high purity regulator high purity? How a Regulator Works High purity applications require equipment that will help maintain the purity of the system. High purity applications are sensitive Loading Mechanism to contamination from elements such as moisture, oxygen, and other gaseous vapors that may be present in ambient air. These contaminants enter the system when the Sensing regulator is removed from the cylinder during Element cylinder changeout, or they may enter through leaks or faulty seals. Delivery Inlet Pressure Pressure The features of a regulator determine the type of service for which it can be used. A Control Element or regulator intended for a high purity Main Valve application has different features than a unit designed for general purpose use. Three main features determine the suitability of a There are three basic operating components in most regulators: a regulator for high purity applications: loading mechanism, a sensing element, and a control element. These three components work together to accomplish pressure reduction. Body Type: Regulator bodies may be of The Loading Mechanism determines the setting of the regulator forged or barstock construction. A forged delivery pressure. Most regulators use a spring as the loading body is formed by casting metal in a mold mechanism. When the regulator hand knob is turned, the spring is under pressure. A barstock body is made by compressed. The force that is placed on the spring is communicated machining out a solid piece of cold-drawn to the sensing element and the control element to achieve the outlet metal bar. Barstock bodies are used for high pressure. purity applications for the following reasons: Barstock Construction The Sensing Element senses the force placed on the spring to set the • Reduced internal volumes: Because delivery pressure. Most regulators use a diaphragm as the sensing barstock bodies are machined, it is possible element. The diaphragms may be constructed of elastomers or metal. to achieve a small internal cavity in the The sensing element communicates this change in force to the control regulator body. The low internal volume element. makes purging the regulator easy, allowing The Control Element is a valve that actually accomplishes the for removal of contaminants like moisture reduction of inlet pressure to outlet pressure. When the regulator and oxygen. It is difficult to achieve a low hand knob is turned, the spring (loading mechanism) is compressed. internal volume in the forging process; The spring displaces the diaphragm (sensing element). The diaphragm forged bodies have more “dead space” and then pushes on the control element, causing it to move away from the tend to trap contaminants, and are more difficult to purge. regulator seat. The orifice becomes larger in order to provide the flow Forged Construction and pressure required. Note: the larger size of the forged body 4 5 • Tight grain structure of the metal: Type of Seals: The seal between The cold drawing process produces the body of the regulator and the metal barstock with a very tight grain diaphragm is important in structure. This tight grain structure maintaining purity. A poor seal prevents the regulator’s internal creates a leakage point through surfaces from adsorbing moisture and which contaminants may enter the contaminants, allowing them to be system. A metal to metal seal purged easily. The forging process (metal regulator body sealing to a produces a more porous grain metal diaphragm) is the most Seal structure; the internal surfaces of a reliable, leak-free type of seal. An Seal between forged body regulator tend to adsorb elastomeric diaphragm can degrade the regulator body contaminants, which eventually find over time, compromising the and the diaphragm their way into the system. integrity of this seal. Some Diaphragm regulator designs incorporate a Regulator • Low Ra surface finish: The machining stainless steel diaphragm that may Body process allows for very low Ra be lined with an elastomer. (roughness average) surface finishes Although the diaphragm is stainless on the barstock. The low Ra finish steel, the seal is created between the minimizes particle shedding, which regulator body and the elastomeric contributes to contamination. It is liner. It is not as reliable as a metal difficult to achieve a low Ra finish in to metal seal. the forging process, making forged bodies susceptible to particle shedding and contamination. Features Influence Cost Diaphragm Material: Diaphragms may be constructed of elastomers A regulator designed for high purity (neoprene, Viton, etc.) or stainless steel. applications is more costly than a Stainless steel diaphragms are used in regulator intended for general high purity regulators because they do purpose use. Barstock bodies are not adsorb and release (or “offgas”) more costly to produce than forged contaminants. When a regulator is bodies due to the high amount of removed from a cylinder, it is exposed machining involved. Stainless steel to ambient air. An elastomeric is a more expensive diaphragm diaphragm will adsorb moisture and material than elastomers. It is any other contaminants from the air. important to remember that not all When the regulator is put back into regulators are created equal when it Diaphragm service, the elastomeric diaphragm comes to features. Regulator releases these contaminants, which Body eventually find their way back into the system. A stainless steel diaphragm is unable to adsorb any contaminants, so it does not contribute to system contamination. 6 7 Dual Stage Regulator Single Stage Regulator Hand Knob 2nd Stage Hand Load Spring 2nd Stage Knob Diaphragm Load Spring Inner Stage 2nd Stage Pressure Control Valve Diaphragm INLET OUTLET 1st Stage OUTLET INLET Diaphragm 1st Stage Control Valve Body 1st Stage Main Valve Load Spring Control Element Single Stage Regulators accomplish the pressure reduction in a Dual Stage Regulators reduce the source pressure down to the single step. Delivery pressure cannot be as tightly controlled as with a desired delivery pressure in two steps. Each stage consists of a spring, dual stage regulator. Single stage regulators should only be used diaphragm, and control valve. The first stage reduces the inlet where an operator can monitor and adjust pressure as needed, or pressure to about three times the maximum working pressure. The where the regulator is supplied a nearly constant source pressure. final pressure reduction occurs in the second stage. Line Regulators are single stage regulators that are used to provide The advantage of a dual stage regulator is its ability to deliver a point-of-use pressure monitoring and control. For example, a lab may constant pressure, even with a decrease in inlet pressure. For have gas cylinders located in a room on the first floor. The gas may be example, as a cylinder of gas is depleted, the cylinder pressure drops. piped up to instruments located in a lab on the second floor. In this Under these conditions, single stage regulators exhibit ‘decaying inlet case, it is difficult to monitor the gas pressure directly at the characteristic’; the delivery pressure increases as a result of a decrease instruments, since the regulators are located on the cylinders on the in inlet pressure. In a dual stage regulator, the second stage first floor. A line regulator may be installed near the instruments for compensates for this increase, providing a constant delivery pressure convenience of monitoring the delivery pressure at the point of use. regardless of inlet pressure. The dual stage regulator is recommended These regulators are installed directly into gas lines, and have a single for applications such as gas supply to analytical instruments, where delivery pressure gauge. constant delivery pressure is critical. 8 9 Section 2 Matheson’s Regulator Product Line Matheson’s regulator products are grouped into two families: Basic Regulator Products, and Specialty Regulator Products. Basic Regulator Specialty Regulator Products Products General Purpose Regulators The specialty regulators are intended • Used with gases that are less than for use with applications that require 99.995% pure particular capabilities, such as low Model 3210 • Used for applications where cost delivery pressures or high flow rates. Deluxe Corrosive Regulator Model 3180 (not purity) is the main concern General Purpose Regulator There are general purpose and high • Economy and deluxe models purity options within the specialty regulator family. High Purity Regulators • Used with gases that are 99.995% • High Pressure Regulators: pure or higher purity Delivery pressures up to 6,000 psig • Used for applications where maintaining system purity is the • Corrosive Service