Please note that when selecting a pressure gauge, it is advisable to consider the following points:
Desired Pressure Range of the Gauge
Typically, manufacturers calibrate pressure gauges in a series of standard ranges, which are almost identical across different manufacturers. Some manufacturers produce special ranges, but on a large scale and for mass production, consumers generally need to follow these standard ranges. Traders also select a portion of these ranges to reduce inventory costs and offer a lower final price to customers. For example, a trader might choose to purchase only the 0–4 bar range from the manufacturer instead of importing 0–1.6 bar and 0–2.5 bar ranges, which can create some limitations in selection.

Diameter of the Pressure Gauge Display
Naturally, the diameter of the manometer dial is also subject to limitations, similar to the pressure range. The most commonly used and standard pressure gauge dial diameters are 63 mm, 100 mm, and 160 mm. Additionally, diameters of 50 mm, 80 mm, and 250 mm are available, but in a limited range.
Thread Type and Size
Pressure gauges are commonly connected using threads according to the NPT and G standards, which are the most widely used types worldwide. In the past, the G thread was widely used in Iran, but today production and usage have shifted toward the NPT standard. Both standards are available in 1/4" and 1/2" sizes. Additionally, you need to decide whether this connection should be located at the bottom or at the back of the pressure gauge.
Pressure Gauge Accuracy
It is usually indicated as CL on the manometer dial, for example, CL1 or CL1.4.
Pressure Gauge Material
Pressure gauges consist of several main components.
Pressure Gauge Body: It can be made of stainless steel, brass, aluminum, carbon steel, plastic, or cast iron.
Internal Mechanism of the Pressure Gauge: It is usually made of brass, phosphor bronze, or stainless steel.
Pressure Gauge Connection: It is made from the same material as the internal mechanism and Bourdon tube inside the gauge.
Horizontal or Vertical Orientation (Bottom or Back Connection) in Pressure Gauge Installation
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