Liquid-Filled Pressure Gauge for Extremely Low Ambient Temperatures

Most pressure gauges work in ambient temperatures as low as −40°F (−40°C). However, around the Arctic Circle, the norm is below −40°F, which is too extreme for conventional pressure gauges to handle. Model PG23LT from WIKA is a high-performance liquid-filled pressure gauge specifically designed for ambient temperatures down to −94°F (−70°C).

A pressure gauge subjected to extremely low ambient temperatures requires a liquid-filled case, as the liquid filling prevents moisture from forming inside the case. Moisture inside the case can cause moving parts to freeze over, thus preventing the pointer from moving. Moisture can also form behind the window, causing it to fog up or, in extreme conditions, to frost over. Either form of moisture prevents a technician from reading the instrument.

Another benefit of the liquid case filling is that it lubricates the internal mechanisms, which extends the life of the pressure gauge when it’s exposed to vibrations, and reduces or eliminates pointer flutter.

Chilly Problems with Standard Liquid-Filled Pressure Gauge

For cold weather use, the oil and gas industry relies on pressure gauges filled with silicone oil. However, this solution is only good for temperatures −40°F (−40°C) and above. Below that, the fill liquid becomes too viscous, resulting in slower response times and inaccurate pressure readings. In extreme cold, the case fill begins to solidify and the gauge might stop working altogether.

That’s why WIKA’s Model PG23LT comes with a special low-temperature silicone case fill, to ensure accurate readings even at extremely low temperatures.

The fill liquid isn’t the only consideration, though. Another critical component to a hermetically sealed and liquid-filled pressure gauge is the elastomers. O-rings and gaskets prevent 1) moisture from entering the case and 2) the case fill from leaking out. Flat gaskets are used to seal the window, the blow-out back at the rear of the case, and the vent valve on top of the case for pressure compensation.

Standard sealing materials, however, will not withstand very low ambient temperatures. Over time, they become brittle and lose their sealing properties. When developing the PG23LT, WIKA engineers eliminated elastomers at critical points. The window seal and O-ring to seal the blow-out back are made from a special material that can withstand extremely low temperatures. The fill plug, normally made of rubber, has been replaced with a stainless steel hex screw or compensating valve, depending on the pressure range.

Model PG23LT: Cool Running in Extremely Low Temperatures

WIKA’s Model PG23LT: a Bourdon tube pressure gauge specially designed to perform well in ambient temperatures as low as −94°F (−70°C).

The PG23LT comes in ranges from 0…10 psi (0.6 bar) up to 0…15,000 psi (1,000 bar). The standard enclosure rating is IP65 per EN/IEC 60529 for pressure ranges up to 230 psi (16 bar) and IP66/IP67 (NEMA 4/4X) for ranges 300 psi (20 bar) and up.

For safety critical applications, the gauge is available in safety design “S3” per EN 837-1 with a blow-out back and a solid baffle wall separating the gauge internals from the window. The PG23LT is supplied with a Certificate of Compliance (2.2 test report) to confirm its suitability for ambient temperatures down to −94°F (−70°C).  If needed, the PG23LT can be supplied with industry approvals such as ATEX. EAC and metrology approvals for export into CIS (Commonwealth of Independent States) countries are also available. Overall, WIKA’s PG23LT is the best solution for all applications in extreme low ambient conditions.

Choosing the right liquid-filled pressure gauge to fit the particular conditions of your application will ensure that your process works properly. Contact WIKA’s experts for help in finding the instrumentation that will maximize your processes’ performance and safety.