How to Select Pressure Gauge in 7 Steps

In this article we will discuss how to select a right pressure gauge in simply 7 steps. We will also guide you about pressure gauges brands available in Pakistan and from where you can find quality pressure gauges at best price in Pakistan.

1. Accuracy 

In simplest form, accuracy is defined as the conformity of an indication to its true value. Accuracy is a percentage of the full range. For example, a gauge that has a scale of 0-300 psi with an accuracy of ±1% would mean that the gauge is accurate to within ± (plus or minus) 3 psi(according to winters.com).

Following are general guidelines:

• Test Gauges and Standards: 0.25% through 0.10% full scale accuracies.
• Critical Processes: 0.5% full scale accuracy.
• General Industrial Processes: 1.0% accuracy.
• Less Critical Commercial Uses: 2.0% accuracy. Refer to ASME B40.100 or the DIN specifications for more information on accuracy.

2. Dial Size

Second important thing in selecting any pressure gauge is the dial size. Pressure gauge dial sizes range from 1-1/2" to 16" diameters. Generally, the important factors involved in determining the dial size are readability requirements, space limitations and required gauge accuracy. 0.25% and 0.5% accuracy pressure gauges usually have dial sizes of 4-1/2" or larger since more dial graduations are required.

In Pakistan most commonly used dial sizes are 2-1/2”, 4-1/2” and 6”.

3. Case Style/Material

The material of the case and its style depends upon the environmental considerations which include ambient temperature, air-borne particulate, condensation, humidity, water and chemicals. All of which can affect performance of the gauge.

Ambient temperature can also affect the accuracy and integrity of the gauge. Gauges manufacturers manufacture gauges temperature compensated and non-temperature compensated. Ambient conditions may require that the gauge be isolated from temperature extremes. In such cases, the gauge should be isolated from temperature extremes with a flexible line assembly.

In corrosive ambient conditions, contain a large number of particulate or in case if the gauge will be exposed to a wet or humid environment like humidity, wash-downs or rain, specify a gauge that is weatherproof/hermetically sealed or liquid filled.

4. Media/Wetted Parts

The Bourdon tube and the socket is considered the wetted parts of the pressure gauge. These parts must be compatible with the process media. If not compatible with the wetted parts of the gauge, then corrosion will occur. Corrosion of gauge wetted parts will ultimately cause gauge failure and probably safety issues. In case of non compatibility of wetted parts and the process media, a diaphragm should be considered.

5. Connection Size

Pressure gauges are available with a variety of connections which include DIN, NPT, JIS, BSP and SAE. Process Pressure Gauges with 2-1/2" dial sizes comes with 1/4" NPT connection and 4-1/2" dial sizes or larger are most often supplied with a 1/2" NPT connection to best support the gauge. Factors to consider when selecting a pressure gauge connection include:

• process pressures
• gauge size and weight
• space limitations
• leak integrity and
• past experience

6. Location of the Connection

When selecting a pressure gauge consider the following mounting options:

• Stem mount lower connect
• Wall/surface mount lower connect
• Panel mount back connect
• U-clamp flush mount back connect, for panel mounting
• Front flange flush mount back connect, for panel mounting

Most commonly used term in Pakistan for stem mount lower connection is "bottom connection".

7. Pressure Range of the Gauge

According to the recommendation of ASME B40.100, the normal operating pressure be confined to 25%-75% of the scale. If there are pulsation in the process, maximum operating gauge pressure should not exceed 50% of the full-scale range.

Pressure Gauges Brands Available in Pakistan

Different brands are available in Pakistan for measuring pressure in the line. Most popular and commonly used brands are:

• WIKA
• ASHCROFT
• WISE
• WINTERS

Chinese manufacturer brands are also available in the Pakistani Industrial Supplies market.

Where to buy Pressure Gauges in Pakistan?

PAKCIA.Com is a reliable source where you can find a range of pressure gauges manufactured by different manufacturers in different dial sizes. Share your process scenario with us and we will recommend you gauges suitable for your process environment and for your budget as well.

Pressure Gauges Price in Pakistan

Pressure gauges price in Pakistan varies from time to time so one can not say something with confidence due to fluctuation of dollar. As price depends upon different factors as mentioned above. Just for an idea we can give you price hint for a pressure gauge of most commonly used dial size 4" with 1/2" Bottom Connection, Normal pressure range, cost you PKR.2500 to PKR.3500 each. European brands are more expensive. For example You can check price for 16 Bar Ashcroft Pressure Gauge Dial Size 4" here. Similarly price for a digital pressure gauge is comparatively high.

Verdict

To properly select a pressure gauge, consider the gauge process, environment, accuracy, pressure range, dial size, connection and mounting requirements.