The control unit incorporates the valves, regulators, gauges, and other components necessary to provide test pressures for instrument calibration. All components are panel-mounted within an aluminum carrying case. An automatic pressure relief valve is installed in the case to relieve both positive and negative pressures, which may build. Quick-disconnect sockets are provided on the control unit panel and on the high-pressure hose for connection of a master gauge and for connection of the control unit to an item under test. The sockets are positive locking and cannot be disengaged when the system is pressurized above 250 psig. A two-position range circuit. The low range shuts off the direct line from the supply source and the test circuit obtains pressure from the regulator circuit at the lower, regulated pressure. The high range applies pressure directly form the supply source to the test control valve. An integral booster pump with a 10:1 amplification ratio accomplishes calibrations at elevated pressures. Precision metering valves provide fingertip control of calibration pressure throughout the range of 0 to 10,000 psig. Final, precise adjustments of the static pressure in the test circuit are accomplished by means of a vernier pressure control. The control contains an automatic relief circuit. An internal nitrogen cylinder with a storage capacity of 90 cubic inches is contained in the control unit. The internal cylinder permits a substantial quantity of low-pressure calibrations to be performed without use of the external nitrogen supply assembly.
Nitrogen Supply Cylinder:
The portable nitrogen supply cylinder is an ICC rated cylinder equipped with a soft seat shutoff valve, pressure gauge, and hose bleed valve. The cylinder can be operated in either horizontal or vertical position. An adjustable nylon belt is provided permitting the unit to be carries on the operator’s back, leaving both hands free. Capacity is 71.2 cubic feet when charged to 2250 psig.
Gauge and Accessory Case Assembly:
The gauge and accessory case assembly contains accessories designed expressly for use with the Portable Pressure Calibration/test System. All of the accessories are housed in a portable, aluminum case lined with shock-absorbent material. Each case assembly contains the following accessory items: six master gauges one diaphragm seal with charging device, one probe kit, one adapter kit, and one packing kit. The master gauges are furnished in standard ranges of 30, 100, 300, 1000, 3000 and 10,000 psig. The probe and adapter kits contain assortments of quick-disconnect probes and threaded adapters. In addition, the adapter kit contains a continuity tester, which can be used, for testing pressure switches or other pressure actuated electrical devices. The packing kit contains individual packing kits for repair of components of the complete calibration system.
Precision Calibration System Offering Extra Value Features:
- The system includes an integral pressure-vernier valve with automatic pressure release for safety. The pressure-vernier valve further enhances the resolution and sensitivity of the high-pressure precision metering valves by allowing for pre- cision “dial-up” or “dial-down” from some selected pressure value.
- The system is safe — all elements of the calibration system are proof tested to 150% of rated pressure. Minimum burst pressure is 400% of rated pressure.
- The system is complete and ready to use… nothing additional need be purchased.
- System sensitivity is excellent throughout its entire range of operation — a HI and LO range switching device assures that the pressure drop across the control valves and the pressure-vernier valve is not excessive, thus providing superior resolution and allowing precision “dial-up” and “dial-down” of the pressure without overshoot.
- System controls are easily operated. The metering valves require no more than 2 inch-pounds of torque to operate even at extreme pressure ranges. Fingertip control is the mode from 0 through 10,000 psig.
Master gauges provide pinpoint accuracy. The gauges are precision, 7-inch dial Bourdon Tube gauges, accurate to +0.1% of full-scale range. Each gauge is protected against overpressurization by an integral safety relief valve.
- Elevated pressures are provided by an integral booster pump capable of providing output pressures of 10 times the source pressure.
- The system is truly portable. The complete system consists of three separate subsystems, the heaviest of which weighs 57 pounds. The three subsystems are as follows: (1) a portable back-pack supply cylinder, (2) a controller and hoses, and (3) a gauge and accessory case assembly which includes the master gauges, adapter kit, and diaphragm seal.
- All calibrations and tests can be accomplished pneumatically. This assures minimum potential contamination hazards, eliminiates potential hydraulic head errors, and provides smooth control of the pressure media. When hydraulic calibrations are required, an essentially error-free diaphragm seal is provided which allows for an ideal interface to the hydraulic unit while still allowing for pneumatic operation of the controller and the master reference gauges.
- The system provides great versatility — the subsystems can be used for other tasks when not in use as a system.