Pressure gauges have been around for many decades, and will be for many more; however users should be aware of the safety issues regarding this vital instrument.
While the Bourdon pressure gauge was first patented in France in 1849 by Eugene Bourdon, the principle of operation has changed little since then and has been widely adopted by industry because of its superior sensitivity, linearity, and accuracy despite the widespread adoption of other digital instruments.
While relatively simply in operation, Norm Robertson, Marketing & Sales Manager with Floyd Instruments, says the correct installation and operation of a pressure gauge is vital for its safe and efficient use.
“The incorrect use of a pressure gauge can cause major damage to a system and serious injuries to the user.
“The user must ensure that a pressure gauge is installed and used in such a way that pressure-related hazards are eliminated to a maximum extent,” Robertson said.
He says it is vital that users check that the pressure gauge is suitable for its planned use in terms of operating pressure (OP) and operating temperature (OT), and in terms of the safety level of the pressure gauge, connection interface and type of mounting.
“Users must also check the compatibility of materials in contact with the fluid to be measured and environmental conditions such as vibrations, shocks, pulses and ambient atmosphere,” he said.
“When used in an oxygen circuit, users must ensure the pressure gauge is designed for such an application. The dial must have the word “OXYGEN” printed in black letters and “USE NO OIL” in red letters.
“The pressure gauge must not have been in contact with oil or grease, or there is a high risk of an explosion,” Robertson warns.
Mountings and connections
When mounting a pressure gauge, Robertson says it must be in compliance with standard practice and advises it to be mounted with an isolation valve.
“The user must also check that the connections are perfectly seated by using suitable seals that are compatible with the fluid to be measured.
“The users must always use a correctly sized spanner to tighten connections, and never twist the gauge’s case to tighten it,” he said.
For pressure gauges fitted with a rear blow-out disc for protection against overpressure, Robertson says there must be a gap of at least 20mm between the rear panel of the casing and the panel immediately next to it.
“Likewise, for this type of rear blow-out disc and a casing filled with damping fluid, users should not remove the disc from its casing,” Robertson said.
When it comes to usage, Robertson warns the pressure gauge must not be subjected to a range of conditions.
“If there is a risk of mechanical shocks, it should be installed at a distance with a hose connection.
“Similarly with a risk of vibrations, it should be installed at a distance with a hose connection or use a liquid filled pressure gauge.
“If there is a risk of pressure pulses, which can considerably shorten the operating life of a gauge, users should mount a pulsation damper.
“For pressures greater than the operating pressure of the gauge, a pressure relief valve should be installed. And if there is a risk of temperatures being greater than operating temperature of the gauge, a syphon should be used or the gauge mounted with a hose connection to reduce the temperature to the pressure gauge,” he said.
If the gauge is being removed from its installation, he warns users to check that the pressure gauge is no longer under pressure, and as a precaution, should be removed slowly.
“Users should also check that residues of the product present in the tube and block of the pressure gauge are not dangerous for the operator and the environment.
“And when it comes to maintenance, verification or recalibration, these operations must be carried out by personnel approved by the manufacturer using suitable equipment,” Robertson warned.