Ashcroft Gauge Filling Procedures

Examples of liquid filled pressure gauges

Liquid-filled, pressure gauges are used to reduce shock and vibration to prevent gauge damage and improve stability and accuracy. Ashcroft is a major manufacturer of gauges and provides guidance for maintenance, including filling procedures.

Manual Filling

Lay the gauge face down and place a 3/8 inch block under the gauge at the 12 o'clock position to allow the air to escape from the fill hole. Pour filling liquid slowly, allowing the air to escape until the oil is approximately 1/16th inch from sealing lip. Remove the block and continue to fill until approximately 1/16th inch from sealing lip. Replace the fill plug and filling is complete.

Vacuum Filling

Vacuum filling is similar to manual filling, except a vacuum pump evacuates the air as it is being filled. This eliminates the need for the block and is a faster method when filling many gauges.

Filling Liquid

The filling liquid used depends on the temperature range and the substance the gauge is measuring. Glycerin is the cheapest and has a temperature range between 20 degrees Fahrenheit and 250 degrees Fahrenheit. Silicone filler extends the temperature range to -40 degrees Fahrenheit to 250 degrees Fahrenheit. Gauges measuring an oxidizing medium should be filled with a halocarbon fluid. Halocarbon has a temperature range of -50 degrees Fahrenheit to 250 degrees Fahrenheit.

References

• Ashcroft: Type 1279 & 1379 Solid Front Duragauge Pressure Gauge Liquid Fill Conversion Instructions
• Ashcroft: Pressure Gauge Installation, Operation and Maintenance