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What are the different parts of a water pressure gauge?

Latest price of water pressure gauges
Water pressure gauge with labelled parts

Water pressure gauge dial indicator

dial The dial indicator allows the user to easily read the pressure gauge.

It consists of a face with a measurement scale on it (typically in bar or PSI, or both), a needle to indicate what pressure the water is at, a lens to protect the dial, a metal case, and a brass connection fitting.

Water pressure gauge, PSI, pounds per square inch

What is PSI?

PSI stands for “Pounds per Square Inch” and is a unit of pressure measurement.

In the UK we measure water pressure in bars, but in America they more commonly use PSI. Many water pressure gauges will have a scale including both measurements.

Water pressure gauge scale and needle

Water pressure gauge with labelled parts, dial indicator, PSI, BAR This scale and needle work together to provide an easily readable visual display that will indicate the pressure of water in a given system.

On this dial indicator, bar measurements are indicated on the red scale and PSI measurements are indicated in black. The needle will move along the scale to indicate the pressure.

Water pressure gauge dial, 11 bar scale

What is the maximum measurement on the scale?

There are many makes and models of water pressure gauge, with varying degrees of minimum and maximum measurements. This model has a maximum measurement of 11 bar which is typical for domestic use.

The maximum measurement varies depending on the type of gauge you are using. Some industrial pressure gauges can measure in excess of 4000 bar!

Wonkee donkee tools DIY guide how to use a water pressure gauge

Water pressure gauge with lazy hand

My water pressure gauge has two needles, what are they for?

Some models of water pressure gauge will have an extra needle (usually red) called a “lazy hand”. When the gauge is initially set, the lazy hand (red) sits right against the regular (black) needle. When the needle rises, it pushes the lazy hand up with it. The regular needle can then drop back down and will leave the lazy hand at the highest reading.

This allows you to record the peak height of water pressure over a period of time, eliminating the need to stand by the gauge and take constant measurements. This is useful if you suspect you are getting pressure spikes at night.

wonkee donkee tools DIY guide how to use a water pressure gauge

Water pressure gauge lens

Water pressure gauge, lens, spare parts, window The lens is there simply to provide a clear window through which you can read the dial and also to protect the dial from damage which may cause the pressure gauge to give a false reading.

Water pressure gauge case

water pressure gauge case, The case holds the inner mechanisms of the dial indicator and the brass connection fitting.

It also protects the inner mechanisms from damage.

Inner mechanisms of a water pressure gauge

water pressure gauge "C" shaped tube bourdon tube water pressure reading PSI wonkee donkee tools DIY guide The inner mechanisms of a water pressure gauge¬†consist of¬†a “C” shaped, hollow spring tube which is closed and sealed at one end.

The other end is sealed and bonded to the threaded connection. When the water enters the tube through the connection, the difference in pressure causes the tube to move in a similar way to a party whistle uncoiling when air is blown into it.

Bourdon water pressure gauge The “C” shaped tube is connected to the geared “movement” mechanism which, in turn, rotates the needle (or pointer) throughout a graduated scale.

The needle’s position relative to the graduations of the scale indicates the pressure.

Brass connection on a water pressure gauge

water pressure gauge brass connection fitting The brass connection on a water pressure gauge allows you to fit it to a threaded hose fitting, outside tap, or water-using appliance.

Braided hose on a water pressure gauge

Water pressure gauge, braided hose, braided steel The braided hose consists of a rubber or plastic inner tube encased in a braided steel outer layer.
water pressure gauge, outside tap, faucet

My water pressure gauge doesn’t have a hose, will it still work?

Yes it will. There are many different makes and models of water pressure gauge and not all of them are sold with hoses.

If your model doesn’t have a hose, don’t worry, you can still fit it to a tap or appliance.

Threaded fitting on a water pressure gauge

3/4 inch threaded fitting, water pressure gauge, BSP fitting A threaded fitting is simply a type of nut that allows you to attach the water pressure gauge to an outside tap or appliance by screwing it onto the interlocking threads.

This fitting has a 3/4 inch (19mm approx.) BSP thread which matches the most common diameter of domestic plumbing fittings.

BSP pipe fittings different sizes

What is BSP?

BSP stands for “British Standard Pipe” and is a family of screw thread types that are internationally recognised as a standard scale of sizes for interconnecting and sealing pipe ends with mating external (male) and internal (female) threads.