The alternative to expensive high accuracy pressure control calibrators is to use a high precision digital pressure sensor.
Primary pressure standards such as dead weight testers offer the highest level of pressure measurement precision and accuracy for most pressure calibration laboratories, but they are mostly manually operated and the results have to be manually converted and typed into a computer or handwritten onto calibration reports.
If you are calibrating a large number of pressure instruments everyday then you will need a more efficient method for pressure calibration which does not compromise on pressure reading accuracy.
Depending on your budget you could invest in a pressure controller calibrator that is computer controlled which will automatically set and read the pressure for you and record the results.
If you are calibrating pressure sensors you can also add a high accuracy digital multi-meter to record the output signal fully automating pressure calibration.
Featured high accuracy digital pressure sensor products
41X Low Range Digital Output Pressure Sensor - Low pressure sensor with a USB, RS232 or RS485 digital output interface for measuring low range gauge or differential pressures from 10 to 300 mbar.
33X High Accuracy Digital Output Pressure Sensor - High precision pressure transducer with an accuracy of 0.05% full scale with a RS485, USB or RS232 digital interface for connecting to a PC.
Pressure sensor manufacturers will add a temperature controlled oven to an automated pressure calibration system so that they can test the performance of the pressure transducer for compensation and characterisation purposes over the operating temperature range. However most pressure calibration laboratories will only calibrate at room temperature and will not include an oven.
The above approach is an expensive one, but if you have the budget, it is the ultimate in high volume high precision pressure calibration. However, if you want to calibrate pressures on a more modest budget then you should look at compromising the sophistication of the pressure control. This is not critical to the pressure reading accuracy although you do need a method of applying pressure in one direction with minimal risk of pressure over-shoot. This will ensure no pressure hysteresis is introduced into an increasing or decreasing pressure set-points. A simple hand pump or pressure regulator can be used for this but the finer the control the easier it will be to set calibration pressures in one direction.
Depending on the pressure calibration accuracy you want to achieve, you will need a pressure sensor that has a very high level of precision. This is because the pressure sensor will need to be regularly calibrated and the accuracy of the sensor will be derived from consideration of the accuracy of the transfer pressure standard used and the precision of the pressure sensor. So the better the precision the better will be the total calibration accuracy.
Featured high accuracy digital pressure sensor products
35X Flush Diaphragm Digital Output Pressure Sensor - Highly accurate digitally compensated pressure transducer with G1/2 male flush pressure port.- 33X High Accuracy Digital Output Pressure Sensor - High precision pressure transducer with an accuracy of 0.05% full scale with a RS485, USB or RS232 digital interface for connecting to a PC.
How often you need to calibrate your reference standard pressure sensor will depend on the long term stability of the sensor technology used inside the pressure sensor. Although a pressure sensor with very good long term stability may seem expensive in the short term, the cost of ownership is going to be much lower because you will not need to calibrate it so often.
To maximise the pressure reading accuracy avoid using an analogue output signal which will introduce extra uncertainties into measurements because the signal will be processed four times before it is recorded by the computer: The sensor element analogue signal is converted to digital and then digitally characterised before being converted back to analogue to provide an output signal from the sensor. Then a digital voltmeter is used to measure the analogue output signal which in turn converts to a digital signal. If you adopt this approach you will introduce the uncertainty of three analogue conversions into the overall calibrator accuracy. You will eliminate two out of the three analogue conversions if you use a pressure sensor with a RS232 or RS485 serial interface, you will fully exploit the full potential accuracy of the pressure sensor.
Featured pressure gauge products
DPT100 Modbus RTU RS485 Differential Pressure Sensor - The DPT 100 is a high-accuracy differential pressure transmitter designed for fast test processes in leakage and flow measurement applications where rapid response time and high sampling rates are essential- 41X Low Range Digital Output Pressure Sensor - Low pressure sensor with a USB, RS232 or RS485 digital output interface for measuring low range gauge or differential pressures from 10 to 300 mbar.
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