5 Gauge Adjustment and Repair Techniques - Calibration Awareness (2023)

The analog pressure gauge is one of the simplest, most used and easiest to calibrate pressure calibration instruments. It has a simple setting where you can easily calibrate. However, the analog pressure gauge is also one of the instruments with the highest number of errors.

Most errors are either "out of tolerance" or the needle is not set to "zero". The following are common problems encountered with an analog pressure gauge:
1. Stuck level indicator.
2. Pressure gauge that does not reset.
3. Pressure reading is too high or out of calibration.
4. the worst thing is that the pressure gauge doesn't work at all

When this happens, do not discard or discard the markers immediately. Fortunately, there are still ways to adjust or repair a pressure gauge.

In this post, I will share with you the following information:
1. 5 ways to adjust the pressure gauge
2. Things to consider before adjusting or repairing
3. how to locate the fault of the pressure gauge and make adjustments.
4. How to certify a pressure gauge.
5. Several useful customization tools

Manometrythey have different uses and therefore have many manufacturing designs.

In this post, I will show you the different settings for different meter models that need to be configured.

Below are some reasons why indicators turn off (out of tolerance or at zero settings):

  1. Changes in altitude and temperature (due to changes in environmental factors).
  2. Bourdon tube overloaded as a result of exposure to overpressure.
  3. Overuse or overexposure to pressure cycling
  4. Exposure to high temperatures and excessive vibration
  5. Wear of mechanical parts.

Things to consider before adjusting or repairing the pressure gauge

Gauge errors can be detected during calibration when we compare gauge readings with a reference standard or pressure calibrator.

Gauge errors can be calculated using the formula:

ERROR = UUT Read - Reference Standard Read

If the detected error is unacceptable or too large based onverification, then adjustment is required.

Whilepressure gauge calibrationprocess and notice the following defects, there is a high probability that adjustment or repair will not be possible.

  1. The reading near full scale is shifted by more than 10% (range shift)
  2. Pressure gauges with a zero offset greater than 25% (zero offset)
  3. Gauges with traces of leakage and body corrosion.
  4. Indicators with needle indicating fault due to excessive friction or wear in motion (loose)
  5. With worn seats and threads.

    When the above symptoms are noticed, there is a good chance that replacement will be your only option.

You can read more in this article fromASCROFT

5 Gauge adjustment or repair techniques

  1. Vent hole to release accumulated pressure
  2. Open the glass (or plastic) cover, then remove the needle.
  3. Turn the screw on the front of the scale.
  4. Adjusting the knob located on the bottom of the manometer
  5. Adjusting the screw located on the gauge needle pointer itself.

Note that the above techniques depend on the design or design of the pressure gauge.

1. Vent to release accumulated pressure

This is the simplest technique. Due to changes in temperature and altitude, the pressure inside the gauge will increase and affect the zero needle settings. This can be fixed by simply opening the pressure relief valve.

Don't forget to re-install or close the vent. Oil may leak and damage the meter.

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This is the simplest of all adjustment techniques and is typically used with most types of oil-filled, permanently sealed analog pressure gauges. If this technique does not solve the problem, the only solution is to replace it. See replacement counter here >>Manometry

2. Open the manometer's protective glass (or plastic cover) and then remove the needle.

For oil-free and non-permanently sealed gauges (most oil gauges are permanently sealed when adjustment or repair is not possible).

However, in some cases where they can be opened, you must first remove the oil from the inside before removing the glass cover. An additional oil change will be required just in case.

If you are wondering what is the name of the liquid filled inside the manometerglycerin or silicone oil. It is important to replace or top up the indicator oil after it has been removed or if the oil has been drained due to a leak.

What are the advantages of an oil pressure gauge?Below are some reasons why the oil level gauge needs to be full of oil:

  1. Oil-filled pressure gauges are better protected against adverse environmental factors as well as moisture and water condensation. Some of the mechanical parts of the pressure gauge become clogged due to dust accumulation and corrosion, resulting in false readings or, worse, damage.
  2. The pressure gauges filled with glycerin oil are also protected against strong vibrations. Strong vibrations affect the mechanical components. Some pins become dislodged or damaged due to strong vibration.
  3. Since the liquid-filled gauge is able to withstand strong shocks, the displayed needle indications are more stable, making them easier to read, which increases the accuracy of the gauge.
  4. Glycerin or silicone oil acts as a lubricant for the mechanical parts, especially the needle tip, giving it a smooth feel.

(At the bottom of the page you will find a tool to easily and safely remove the cap and pin).

In some cases, when releasing accumulated pressure does not solve the problem, we can make the following adjustment by opening the pressure gauge, removing its protective cover and removing the needle indicator. With this method, we can correct the instrument's zero offset and range when it occurs.

A. To fix zero shift:

After removing the cover, do the following:
1. Pull out the needle with the needle puller (see below).
2. After removing the needle, set it to the zero scale and then push it back.
3. Check the reading by applying pressure

How to check the pressure gauge? Continue reading...

B. To fix range offset:

After removing the needle, do the following:
1. Connect the pressure gauge to a known pressure source (e.gElectronic self-weight regulatortheFluke 754 with a set of pressure units)
2. Increase the pressure to approximately 50% of full scale. After setting the pressure, return the needle to the same value as the pressure supplied. For example, increase the pressure by 100 psi over the reference standard, then attach a needle to the 100 psi scale reading on the pressure gauge.
3. Check that it is now within the acceptable range.

In most cases, just doing A or B fixes the problem.

3. Adjustment with the button located on the bottom of the manometer

Some pressure gauges have an adjustable knob on the bottom of the body. It is a diaphragm pressure gauge commonly used in water treatment pipelines.

Just remove the lock and the knob will turn freely to adjust the needle.

4. Adjusting the screw inside the pressure gauge mechanism

Some pressure gauges have an adjustment screw inside the body, on the back of the needle or on the front of the dial. This type of meter is used on gas pipelines.

Access the screw inside the meter by removing the cover. Turn the screw clockwise or counterclockwise to return the needle to the zero position.

Perform a post-zero check.


5. Adjustment with the screw located on the counter needle pointer

This applies to some pressure gauges that have an adjustable screw built into the needle itself. After removing the cover, use a screwdriver and carefully turn the screw to insert the needle. Take a look at the image above or watch the video below.

Based on the photo above, I have shown you the location of the screw and the location of the screwdriver, however, when turning the screw, you need to hold the needle to turn the screw and make adjustments.

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Be more careful with this kind of customization. the needle is connected with a spring inside and is very sensitive. Excessive force when turning the screw may damage the entire connection or the pressure gauge.

After adjustment, do not forget to check the pressure gauge.

Pressure gauge adjustment and control...

The technique of adjusting and checking the pressure gauge - a real demonstration

How to check the accuracy of the pressure gauge after adjustment?

Every time we make an adjustment or calibration, we must verify that the readings are within the acceptable range, tolerance or acceptance criteria of the gauge.

Before adjusting, it is necessary to consider what tolerance should be observed.

Tolerance or acceptance criteria are based on:
1. Manufacturer's data.
2. user or process tolerance.
3. International standards or regulatory requirements (e.g. ASTM or ISO standards)

For example, we will use the manufacturer's specifications to check the pressure gauge. Below are the steps:

1.Determine the degree of accuracy (accuracy class) of the manometer. Most pressure gauges have an accuracy class printed on the dial (see illustration below). This accuracy class has an equivalent MPE (Maximum Permissible Error), where we can calculate the limits of the tolerable error.

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For more information on the relationship and differences between precision, error, tolerance and uncertainty, see my other post at this link>>precision-error tolerance-uncertainty

2. Convert the accuracy class to a decimal number by dividing by 100, then multiply by the range or FS reading. This rating is expressed as a percentage of the total scale or range. Based on the photo above, the meter shows a KL of 1.6 which is 1.6% of full scale and a class of 1% which is equal to 1% of range (see example below).

Difference between full scale and range on the meter display

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Skala Puna (FS)The reading corresponds to the maximum value displayed on the pressure gauge. It is a range from ZERO to maximum.

Rangeis the difference between the lowest range (not zero) and the highest range. The tolerance range applies to pressure gauges with a negative value (see picture of the pressure gauge in the upper right corner).

Range = 5 - (-1) = 6

Span and full scale readings are the same when the lower range is ZERO.

To determine the tolerance limit, we will multiply the accuracy class by the range or FS reading. See example below.

  • The pressure gauge is accurate to 1.6% of full scale (FS)
    • The full scale reading is = 7 bar

tolerance = (1.6/100) x 7 = 0.112 bar

  • So the reading must be insideOnly +/- 0.112

3. Once tolerance limits or acceptance criteria have been established, generate the necessary pressure requirements and then compare the measurements. If the reading is outside this range, additional adjustments are required.

If you have made any or all of the above adjustments and the pressure gauge is still out of tolerance, then it is already faulty and your only option is to replace it or have it seriously repaired.

Some useful tools when customizing

  1. Jack Needle Puller Hand Gauge Set. With this tool, you can safely and effectively remove the needle:
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Click here to checkAmazon

When removing the pin, be careful not to pull it too hard to avoid damaging the pinion mechanism. Some pins are too narrow to pull the gear. To avoid this, you can use this tool.

2. A set of key straps. Use this tool to safely and easily remove the glass cover.

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Watch the video here on my Facebook page:How to use a bar wrench


In this article, I have shared the following information:
1. 5 ways to adjust the pressure gauge,
2. Things to consider before adjusting or repairing
3. how to locate the fault of the pressure gauge and make adjustments.
4. How to certify a pressure gauge.
5. Several useful customization tools

You can save the meter and reuse it by performing regular calibrations and adjustments, monitoring or choosing the correct setting for your particular meter as explained in this article.

If you have other methods of adjusting or repairing pressure gauges, please do not hesitate to comment.

To learn how to calibrate a pressure gauge, visit this post:Calibrating-a-sphygmomanometer-with-the-fluke-754-process-calibrator-with-a-set-of-pressure-modules

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