How To Calibrate SH308 Pressure transmitter ?

SH308 Series Pressure transmitters can be used to measure pressure value in the process control. It is a kind of economical pressure sensors with good price also with stable functions. But Pressure transmitters need calibration after long time use, or when the pressure is not accurate, below is the procedures how to calibrate pressure transmitters:

Pressure sensor Calibration

1. All the pressure transmitters have been calibrated before leaving the factory, and no calibration needed.

2. SH308 Pressure transmitter Calibration needed in following cases

a) Drop, vibration or crash the pressure transducers during the transportation.

b) The pressure transmitters have been kept without use for more than 6 months.

c) After long time operation, error appears.

d) Routine inspection for the pressure transmitters

3. Calibration instruments needed

Product	Specification	Accuracy	Quantity
Stabilized voltage supply	(0-30)VDC/1ADC	±2%	1 unit
DigitalMultimeter	(0-30)VDC/20mADC	±0.05%	1 unit
Pressure Signal Generator	As per pressure range	±0.05%	1 unit
Resistance box	ZX21/1000Ω		1 unit

Note: Calibration instruments and environment should meet specifications of pressure transmitter’s calibration regulations.

4. Calibration procedures

For example: Pressure transmitter, range(0-50)Kpa, output 4-20mA,accuracy 0.5,B type connection box.

a) Connect the calibration instruments and transmitters as following:

1. Pressure Signal Generator	5. Resistance box (load)
2. Stop Valve	6. Ampere meter
3. Vent Valve	7.Stabilized voltage supply
4. Leveltransmitter

b) After open the housing of the pressure transmitters, and we can see “S”,“Z” adjusters.

c) Add pressure on the transmitters for 3 times, and keep it for 10 second in rated pressure, return to zero point after each load.

d) Close 2, open 3, and let the transmitters vent to air, adjust “Z” adjuster, and let the ampere meter show “4.00mA".

e) Close 3,open 2,and add the pressure transmitters with full range pressure, for example: 50kpa.

When the pressure is stable, adjust “S” adjuster, and let the ampere meter show “20.00mA". (Note: zero point and full range output should be calibrated for several times)

f) Calibration points should not be less than 5 points (including zero point and full range point).even selected the calibration points according the pressure range. For each calibration point, it should be keep stable for 20 second then read the output value.

g) Add the pressure step by step according to the selected points, when reaching the upper limit of the rated pressure; add the pressure to 110% of the rated range for 1 minute, then decrease the pressure to rated range, read the value after 20 second as the full range output value. Decrease the pressure to the lower limit of the range, and take it as a circulation. Each pressure transmitter needs 3 circulations.

h) After calibration, assemble the pressure transmitters and fix each part tightly.

Warranty when calibration SH308 series Pressure Transmitters

Free charge repairs for 12 months after delivery the pressure transmitters on conditions that: the defect products are caused by material or process which is not meeting the requirements of the contacts.

Diaphragm deformation or other improper usages to cause the broken is not belonging to free charge repair.