Operation and Maintenance of a Pressure Gauge
- Inspection Frequency
The frequency of inspection is dependent on the severity of service and how critical the accuracy of the indicating pressure is. The inspection frequency can range from monthly to annual basis. To ensure the accuracy of your pressure readings it is strongly recommended that all pressure gauges be recalibrated and certified each year. Rhomberg Instruments provides test certification that are traceable to the SANAS .
- Isolating Valves
It is recommended that isolating valves be fitted with the gauge. This enables the gauge to be removed at any time for checking, recalibration or replacing without interruption to the process. The valves should be opened or closed slowly to avoid sudden changes to pressure being applied to the gauge. It is recommended for systems that have an abrupt pressure surge at start-up to close the valves during initial start-up.
Brass wetted parts are suitable for use on the following types of media: air, oil, water and other non-corrosive fluids. For corrosive fluids, stainless steel should be specified. For special applications, other materials such as Monel® can be used as well. Diaphragm seals may also be considered.
If pressures are expected to pulsate violently, oscillate with high frequency or occur with sudden shock, a snubber should be considered. Winters’ snubbers incorporate sintered porous 316 stainless steel snubbing element with a large surface area to ensure long term effectiveness on most pressure media. Snubbers are available in three viscosity classifications: heavy oil, water and air. Brass, stainless steel or Monel® housing can be specified depending upon the media used.
All pressure gauges should be placed in dry storage under ambient room temperatures. It is recommended to store pressure gauges in their original packing boxes.
Installation of a Pressure Gauge
Vibration and extreme ambient temperatures can affect the dial reading of the pressure gauge. These areas should be avoided as much as possible.
A suitable thread sealant is required for NPT threads such as pipe dope or Teflon® tape. Never use any part of the pressure gauge other than the wrench flats that is on the gauge socket. Always tighten with an open end or
adjustable wrench on the wrench flats. Failure to do so will severely damage the pressure gauge.
- Venting Procedures
Due to pressure build up, some gauges (usually lower pressure ranges such as vacuum, up to 700 kPa) may reflect a reading that is slightly “off zero”. To properly “vent” the pressure gauge, cut off the tip of the fill plug after you have installed the instrument. This allows the gauge to be equal to the atmospheric pressure.