HUMIDITY TRANSMITTERS

HCT-841 DEW POINT, MOISTURE & TEMPERATURE TRANSMITTER ❑ High Performance ❑ Thin Film Technology HCT-841-B-02-D1-X20 ❑ Reduced Maintenance ❑ High Temperature HCT-841-B-12-D1-X20 Operation to 185¡C ❑ Capable of 100+¡C Dew Point Depression ❑ Low Dew Point HCT-841-A-08-D1-X21 Operation to -60¡C ❑ 0.05¡C Dry Bulb environmental test chambers, dehumidi- Accuracy Free of Routine fication systems and many others. Maintenance ❑ Unlike other dew point instruments, Unequaled Contam- High Value with High ination Resistance the HyCal HCT-841 does not require Performance frequent periodic servicing, cleaning ❑ Digital Signal The HCT-841 Transmitter combines or sensor replacement. The architecture the key features of well-proven sensor of the sensor provides strong immunity Processing technology, advanced probe design and to airborne contaminants. And the sen- ❑ digital signal processing in a rugged low sor's material is a thermoset polymer High Performance cost package. HyCal has once again set which is inherently very inert. The result Probe Design the standard of value for high perfor- is a sensor free of systemic drift charac- mance moisture measurement, and its teristics, which is not the case with other ❑ Easy Installation maintenance requirements (traditionally thermoplastic or aluminum oxide type the biggest cost factor in dew point mea- humidity sensors. Some unusual applica- ❑ Loop Powered Dual surement) are very low. This means that tions characterized by extreme levels of 4-20 mA Outputs the HCT-841 is not only inexpensive to contaminants such as dirt, ash or oil install, but also inexpensive to own and vapors may require occasional cleaning The HCT-841 Dew Point and Temp- operate. of the HCT-841 sensor and/or the sin- erature Transmitter offers high perfor- tered stainless steel sensor filter. In this mance water vapor measurement capa- situation, the cleaning can typically be bilities over a very wide range of both Advanced Thin Film performed by using a simple pump moisture and temperature. It measures Sensor Technology spray bottle filled with a solution of iso- in-situ with an advanced solid state dual The HCT-841 sensor assembly propyl alcohol (common rubbing alco- element sensor assembly that is able to employs well-proven high performance hol). Such cleaning does not affect cali- survive very harsh conditions. The HCT- thin film moisture and temperature sens- bration. For most applications, however, 841 is economically priced, has no rou- ing elements, both manufactured by the unit is maintenance free. Whether a tine maintenance requirements, and its HyCal in the USA. The capacitance Archived Documentnew installation, or a replacement instal- moisture output signal can be scaled to a moisture sensor is constructed of layers lation, the HCT-841 will provide quick variety of psychrometric units. End of thermoset polymer. The temperature payback and added value through signif- users will find it ideal for installation in sensor is the world's smallest thin film icantly reduced maintenance manhours. a wide variety of systems and equip- RTD. Both have been qualified for use Original equipment manufacturers who ment, including environmental control in various military and aerospace pro- employ the HCT-841 can count on fewer systems, instrument air lines, high tem- jects. They help to assure the long term service problems, greater customer satis- perature drying equipment, dry gas sys- accuracy and reliability of the HCT-841. faction and the marketing edge that tems, emission monitoring equipment,

Distributed by Kele ¥ www.kele.com ¥ USA 901-937-4900 ¥ International 901-382-6084 41 HUMIDITY TRANSMITTERS comes from increased system perfor- 0.05¡C Dry Bulb It obtains the temperature value via a mance. 12-bit ND converter. It checks the inter- Accuracy nal characterization data, and by use of a The HCT-841 uses HyCal's own 12-bit D/A converter, updates the dew High Temperature TM precision ULTRA-7 thin film platinum point 4-20 mA signal. It does all of this Operation to 185¡C RTD for dry bulb temperature measure- in less than a third of a second. The dig- The HCT-841 sensor is designed to ment. System calibration in highly accu- ital scheme also allows alternative out- operate continuously at temperatures of rate temperature calibration baths put units such as humidity ratio (lb/lb), 185¡C (365¡F) and will survive brief ensures outstanding ±0.05¡C (±0.09¡F) wet bulb temperature and relative excursions to 204¡C (400¡F). Many accuracy over the transmitter’s full dry humidity. HyCal fully calibrates every applications which previously required bulb temperature span. The unit’s analog unit against accurate reference standards sampling systems can now be measured temperature transmitter section directly and encloses a calibration certificate, in-situ with the HCT-841. For unusually generates a linear, highly stable 4-20 traceable to NIST, with each unit. high temperature applications, refer to mA current signal which is suitable for accessory data sheet PD-536.0. applications that demand high precision. High Performance Capable of 100+¡C Dew Unequaled Contamina- Probe Design The HCT-841 utilizes an advanced Point Depression tion Resistance probe design which virtually eliminates Chilled sensor systems literally The HCT-841 sensor assembly is temperature effects and parasitic capaci- "depress" the temperature of a sensor highly resistant to both chemical and air- tance. New materials and sensor assem- until dew or frost forms, thus dew point borne contaminants. The bottom sensing bly techniques greatly enhance perfor- depression is simply the difference layer is a very inert thermoset polymer mance in any environment, especially in between the dry bulb and dew point whose dielectric constant changes in high temperature and/or high dew point temperatures. The HCT-841 sensor, response to changing vapor pressure. A depression conditions. Every probe used unlike chilled sensors, remains at operat- porous platinum layer over the sensing on model HCT-841-B is tested for com- ing temperature and is not cooled to the polymer layer serves to reflect and con- pliance with its 350 psig pressure speci- actual dew point temperature. The maxi- tain the sensing capacitance field so that fication. The probe passes a bubble leak mum depression capability of the HCT- surface contaminants do not affect the test, but it is not considered hermetically 841 depends on the dry bulb temperature sensor’s accuracy. A final polymer top- sealed. at the sensor. At high temperatures, it coat provides physical protection. will easily measure dew points which Response time may be slowed by a layer are more than 100¡C (212¡F) below dry of surface contaminants, but as long as Direct Immersion / bulb. See the Minimum Dew Point water vapor pressure can equilibrate Easy Installation Capability graph for more detail. across the contaminant layer, the accura- The HCT-841's sensor is designed cy is unaffected. This rugged sensor is for direct immersion into the air stream Low Dew Point unique in that it may be washed. If or other bulk gas to be measured. The Operation to -60¡C physical damage occurs, a new sensor HCT-841-A is normally mounted by The specially ranged "D3" and "H3" may be plugged in and the system recal- attaching the housing's mounting feet to versions of the HCT-841 provide reliable ibrated. Temporary condensing condi- the wall of a duct or to any flat surface. measurements of frost point as low as tions are not a problem. The HCT-841-B uses the same housing, -60¡C (-76¡F) at temperatures approach- but its probe has a 1/2" NPT fitting, ing 20¡C. Even at temperatures as high Digital Signal which is typically used to mount the as 40¡C (104¡F), this unit will still mea- Processing unit, especially in pressurized lines or sure frost points as low as -50¡C containments. The HCT-841 does not attempt to (-58¡F). This represents outstanding dew utilize imprecise analog humidity sig- point depression capability for dry gas Archivednals. Its sensor assembly Document is precisely Easy Field Calibration and instrument air applications. A frost characterized for both temperature and Unlike other dew point instruments, point of -50¡C (-58¡F) is equal to 40 moisture response. The microprocessor the HCT-841 does not require periodic PPMw (0.28 grains/lb) at one atmo- in the HCT-841 processes the capacitive recalibration. However, if recalibration sphere operating pressure, only 2 PPMw signal from the ULTRA-DTM sensor is desired in order to meet internal quali- at 350 psig. (Refer to the Minimum Dew directly in digital format. Then, from the ty standards, or if a damaged sensor is Point Capability graph for more detail.) analog temperature transmitter section. replaced, then a simple two point cali- bration can be performed with the

42 Distributed by Kele ¥ www.kele.com ¥ USA 901-937-4900 ¥ International 901-382-6084 HUMIDITY TRANSMITTERS optional HPK-2 field calibration kit. nal factory calibration can easily be Loop Powered, Dual This kit includes a dry gas standard and restored. Both the dry and wet standards a wet gas standard. The dry gas standard must be used when the sensor is 4-20 mA Outputs consists of a chemical molecular sieve replaced. The HCT-841 is powered by user- (high performance desiccant), which is Because the thin film platinum RTD supplied DC loop power (24 VDC nomi- placed into an aluminum bottle that is temperature sensor is inherently very nal, 45 VDC maximum). There are two fitted over the probe. After a brief peri- stable over the HCT-841's operating individual 2-wire 4-20 mA output sig- od, a DIP switch in the instrument is range, and because the temperature sec- nals, one for dry bulb temperature and moved, and the microprocessor sets its tion is very tightly calibrated, tempera- the second for dew point temperature or own zero. The wet gas standard is a ture calibration should not normally be other moisture unit. For proper opera- 75.3% relative humidity saturated salt adjusted in the field unless the calibra- tion, both loops must be powered, even cell (pure sodium chloride and distilled tion equipment is accurate to 0.01¡C if only one signal is being used. Only water). Another DIP switch changes the (0.02¡F). Since the temperature section three wires are required, since the posi- instrument’s output to relative humidity is analog, temperature calibration data is tive DC connection is common to both for the wet gas calibration. Normally, not stored digitally. Instead, convention- loops. only the wet gas standard is used for al non-interacting zero and span trim routine calibration checks. If an error is pots are provided. made in moisture calibration, the origi- How the HyCal Moisture Sensor Works

❑ Water vapor within the sensor equili- brates with the water vapor in the sur- rounding gas. ❑ The capacitance of the dielectric poly- mer sensing layer changes with the changing concentration of water vapor molecules, which are electrically polar. ❑ Gold-plated electrode fingers are embedded within the sensing layer. The electronics of the HCT-841 connects with these electrodes in order to read sensor capacitance. ❑ The porous platinum layer reflects and contains the capacitance field so that the sensor does not "see" contaminants on the surface. ❑ The protective polymer top layer pro- vides physical protection against air- borne contaminants. ❑ Surface dirt does not affect the accura- cy of the sensor. A heavy contaminant layer will slow down the sensor's Archived Documentresponse time because it will take longer for water vapor to equilibrate in the sensor. ❑ HyCal's thin film Platinum RTD is of the same thermal mass as the moisture sensor. This is a significant advantage for final signal accuracy.

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HCT-841

Ordering Information - HCT-841 High Performance Dew Point and Temperature Transmitters

HCT-841-A Dew point and temperature transmitter Base Model HCT-841-B Dew point and temperature transmitter with 1/2 x 1/2 NPT fitting on 350 psi probe 08 8" probe, HCT-841-A only Probe 02 2" probe, HCT-841-B only Length 12 12" probe, HCT-841-B only D1 Dew point: -104.7¡C to 100¡C; Dry-bulb: 0¡C to 204.7¡C D2 Dew point: -12.8¡C to 28.15¡C; Dry-bulb: 0¡C to 40.94¡C D3 Dew point: -60¡C to 42.3¡C; Dry-bulb: -50¡C to 52.3¡C D4 Dew point: 0¡F to 100¡F; Dry-bulb: 0¡F to 200¡F Range and H1 Humidity ratio: 0.0 to 0.5 lb H20/lb dry air; Dry-bulb: 0¡C to 204.7¡C Output Options H2 Humidity ratio: 0.0 to 0.024 lb H20/lb dry air; Dry-bulb: 0¡C to 40.94¡C H3 Humidity ratio: 0.0 to 0.05 lb H20/lb dry air; Dry-bulb: -50¡C to 52.3¡C R1 Relative humidity: 0-100%; Dry-bulb: 0¡C to 204.7¡C W1 Wet-bulb: -10¡C to 100¡C; Dry-bulb: 0¡C to 204.7¡C X20 Duct mount for HCT-841-A of HCT-841-B Mounting X21 Wall mount for HCT-841-A only Options X52 PVC solar probe shield for use outdoors Option

HPK-2 Field calibration kit, includes dry gas and wet gas standards 433-0151 Sensor shield (sintered SS, no hydrophobic coating) Accessories 433-0188 Sensor shield (sintered SS, with hydrophobic coating) and Spares 433-0155 Sensor shield (fluted black composite) 433-0194 Replacement dual element sensor assembly

Archived Document

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To use the dew point accuracy graphs, first determine the operating temperature and dew point for the application. For exam- ple, if a D1 unit is measuring a dry bulb tem- perature of 150¡C and a dew point of 50¡C, then locate the 150¡C point on the X-axis of the D1 graph. Follow a line straight up until it meets the dark slanted line labeled "50¡C DP." From this intersection point, follow a line straight left to the Y-axis. That point repre- sents accuracy of about ±4.5¡C. The D3 unit, for example, has dew point accuracy of about ±2¡C when dry bulb is 20¡C and frost point is -30¡C.

The lowest dew point that the HCT-841 can read is largely a function of the dry bulb tem- HHCT-841 Minimum Dew Point Capability °F perature at the sensor, with specific limits -40 -4 32 68 104 140 176 212 248 284 320 356 392 imposed by internal software. This graph 0 32 applies to the D1, H1, D3, and H3 units (refer to the Code 2 output options as shown in the -10 14 Ordering Information table). At 40¡C (104¡F) dry -20 -4 bulb, for example, the HCT-841 will read frost D1 & H1 points no lower than about -32¡C (-25.6¡F), -30 units -22 even though its 4-20 mA dew point scan is D1 & H1 units scaled downArchived to -104.7¡C (-156.46¡F) for the D1 -40 Document -40 unit, and to -60¡C (-76¡F) for the D3 unit. To -50 -58 read low dew points at even higher tempera- tures, request information on the X81 cooler -60 -76 Dew Point Temperature Point Dew accessory. (The H1 and H3 units are equivalent to the D1 and D3 units except that their output -70 -94 -40 -20 0 20 40 60 80 100 120 140 160 180 200 signals are scaled for humidity ratio, i.e lb/lb or °C PPMw, rather than dew point.) Dry Bulb Temperature

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HCT-841 General Specifications:

Performance Moisture Dry Bulb Temperature

Sensing Element: ULTRA-D IITM ULTRA-7TM 1000Ω Pt RTD Calibrated Accuracy: See accuracy charts +/- 0.05¡C (0.09¡F) over the full span Calibration Certificate: NIST traceable data supplied NIST traceable data supplied Outputs: 4-20 mA, linear 4-20 mA, linear (See ordering information for available ranges and output units) Signal Update: 3 times per second Continuous Analog Input Voltage Effect: 0.002% Vmax. (negligible) from 11 to 45 VDC Time Constant: 16 seconds in slowly moving air at 25¡C with fluted shield 50 seconds in slowly moving air at 25¡C with sintered stainless steel filter Installation Transmitter Housing: Coated steel, rated NEMA 4X Sensor Housing: Stainless steel probe; porous stainless steel filters; fluted shield Sensor Operating Environment: -50¡C to 185¡C (-58¡F to 365¡F) Transmitter Operating Environment: -40¡C to 80¡C (-40¡F to 176¡F) Storage Environment: -55¡C to 85¡C (-67¡F to 185¡F) Power Requirements: 11 VDC + (Rload x 0.02 A) min to 45 VDC max for dual 2-wire operation (Requires three wires for installation, even if monitoring only one signal) Signal Connection: Screw terminals Sensor Mounting: 1/2" NPT probe fitting or mounting flanges on housing Dual sensor assembly plugs in to probe with 4 gold plated pins Pressure: 0 psig to 350 psig for HCT-841-B. (In pressure, max dew point of 100¡C for D1 version) 0 psig to 50 psig for HCT-841-A Serviceability Periodic Maintenance: Maintenance free, verify calibration periodically, wash sensor as needed Adjustments: Vernier, non-interacting, multi-turn potentiometers for zero and span control of dry bulb temperature. Momentary push-button switches for moisture signal calibration; adjustments are accessed by removing the top cover RTD Sensor Short Indication: Dry bulb temperature signal goes downscale to 4.0 ±0.01 mA (useful for system check) Over temperature Indication: H20 signal upscale at 192¡C db (D1, H1, W1, R1), 38.4¡C (D2l H2), or 46.0¡C (D3, H3) Sensor Cleaning: Wash with detergent solution and deionized water rinse, can also use isopropyl alcohol, camel hair (organic) brush may be used during cleaning when required

CONDUIT HUB 1/2” NPT

CONDUIT HUB 2.25 NOM. 1/2” NPT MALE HEX NIPPLE 300 SERIES SST Archived DocumentPROCESS CONNECTION 1/2” NPT

2” OR 12” STD 9/32” x 7-32” (4 PLACES)

9/32” x 7-32” (4 PLACES)

SHOWN WITH X21 PROBE MOUNTING SHOWN WITH X20 PROBE MOUNTING (INTEGRAL PROBE, ROOM MOUNT) (INTEGRAL PROBE, DUCT MOUNT) HCT-841-A-X21 OPTION HCT-841-A-X20 OPTION HCT-841-B SIDE VIEW

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