Digital manometers are capable of measuring accurate positive, negative and differential pressures. The devices come in various sizes and can withstand water pressure up to around 150 PSI (pound force per square inch). Digital manometers also convert pressure units for you if needed. In addition they include memory functions allowing you to save your previous measurements.
Make sure the component has the proper battery installed. Most manometers have screws holding the protective cap to the battery compartment. Unscrew and check to make sure a battery is installed.
Look for the ON/OFF control on the manometer. Press the control to turn the device on.
Recalibrate the device by re-zeroing it immediately when you turn the device on. This will ensure that you do no have any inaccurate measurements. Open and vent both ports of the device so that no pressure is occurring. Press the "Zero" key.
Check with your manual to see what tubing your barbed connections fit. Obtain a positive pressure by connecting your tubing to the positive port and venting the negative port. Obtain a negative pressure by connecting your tubing to the negative port and venting the positive port. Venting allows for the port to be at atmospheric pressure. Obtain differential pressure by connecting the higher
pressure to the positive port marked and connecting the lower pressure to the negative port.
Change your pressure units by locating the "Units" key. You can then select your choice of metric pressure unit.
Save your pressure results by pressing the "Store" key.