There are various types of gauges available on the market. These include Analog, Digital and Pneumofathometer models. You need to find the right gauge for your diving needs. It is important to calibrate your gauge at all altitudes for safety decompression.
Analog gauges
Analog gauges for gauge diving can help divers understand the depth in the water. They work by having a needle pivot around a graduated scale to indicate the depth. These gauges can be worn around the wrist or integrated into a dive computer. While the analog gauges are more reliable than digital ones, they may not be as accurate. An analog gauge offers the advantage that you won't run low on batteries.
The face of the gauge is designed to be easy to read. It has numerical increments of depth ranging from 10'-40' and 20’ to 150'. It also has a pressure gauge. It can display pressure from 0 - 5000 psi. The red screen represents reserve air, while green indicates main air.
Digital models
Many divers desire to dive deep and stay there, but a digital gauge can't be used. Temperature variations can alter the pressure differential between the gauge (and the ambient water). A mechanical gauge is safer than an electronic one. A gauge not only keeps track of dive time and depth but it also calculates Nitrogen retention and helps prevent decompression illness.
There are two types of digital gauge dive computers. The hose method is a simple method, using a hose to connect the dive computer to the high-pressure port on the first stage. The wireless mode connects to the dive computer using an electronic transmitter attached at the first stage. This type can be used with console and wrist-mounted models.
Pneumofathometers
Pneumofathometers can be used to measure the depth of air that is supplied to divers. These devices measure the air pressure near the surface and then display the depth in feet (or metres). These devices were used to be mounted on an air pump that provided breathing air for standard diving suits. The air supply was free flowing, with no back pressure.
For gauge diving, divers should buy a gauge that is between 130-160 percent of the maximum operating temperature of their diving system. This range should be adequate for systems that operate at 3,000psi.
Submersible pressure gauges
Submersible pressure gauges (SPG) are devices that allow divers to monitor their air pressure. It can display current depth and indicate the direction in which the diver is moving. The regulator is connected to the SPG via a high pressure hose. This arrangement is useful for divers to avoid getting confused about the location of the gauge and helps prevent it from being lost. The SPG indicates the remaining air pressure, in pounds per sq inch. It can be used for air supply monitoring while diving.
Scubapro manufactures an oil-filled, analog depth gauge. The Bourdon tube design measures down to 200 feet. It comes with a C1 Compass, which attaches directly to the console boot. Because it is easy to use, this gauge is ideal for beginners.
Compass
It is important to be able to read the compass easily when gauge diving. It should have adequate markings to suit your needs and be large enough to be readable underwater. You will want a compass that has a bezel with indicator marks at every five degrees and compass headings in increments of 30 degrees.
A gauge diver's compass should have a side view window to allow them to see the direction it is pointing. This allows the diver, even in total darkness, to follow the compass's course.