Pressure Detector Functions
Although the pressures monitored vary slightly depending on the design details of the facility, all pressure detectors are used to provide up to three main functions: indication, alarm and control. Since the fluid system may operate in both saturated and undersaturated conditions, an accurate pressure indicator must be available to maintain proper cooling. Some pressure detectors have audible and visual alarms when a preset limit is exceeded. Some pressure detector applications are used as input to protective features and control functions.
If a pressure tool fails, spare detector elements should be installed. If spare gauges are not installed, the pressure may be read on an independent local mechanical gauge if available, or an accurate pressure gauge may be installed at a suitable point in the system. If the detector is functional, pressure readings can be obtained by measuring the voltage or current values across the detector probe and comparing these readings to the calibration curves.
Pressure instruments are sensitive to atmospheric pressure changes around the detector. This is especially evident when the detector is located in an enclosed space. A change in the pressure around the detector causes a change in the indicator pressure from the detector. This greatly reduces the accuracy of the pressure device and must be taken into account when installing and maintaining these tools. Ambient temperature changes affect the accuracy and reliability of the pressure detection tool. Changes in ambient temperature can directly affect the resistance of components in the instrumentation circuit and thus affect the calibration of electrical/electronic equipment. The effects of temperature changes are reduced by circuit design and by keeping the pressure sensing device in the proper environment. Moisture will also affect most electrical equipment, especially electronic equipment. High humidity causes moisture to accumulate on the equipment. This moisture can cause short circuits, grounds, and corrosion, which in turn may damage components. The effects of humidity are controlled by keeping the equipment in a suitable environment.
The three functions of the pressure control tool and the alternating pressure methods for control are summarized below.
Pressure detectors perform the following basic functions:
- the sign
If a pressure detector is disabled:
- A spare detector element may be used (if installed).
- Local mechanical pressure can be used (if available).
- A precision pressure gauge may be installed in the system.
- atmospheric pressure
- environment temperature
Rose Calibration Company in Melbourne, Australia with over ten years of experience provides all calibration, maintenance, and repair services throughout Australia. If you live in Sydney, Melbourne, Adelaide, Perth, Geelong, and Brisbane, you can receive your quote in less than two hours by fill-up the form via the “Booking” link.