This artical provides tips on maintaining pressure gauges and troubleshooting solutions used in the process control industry.
Pressure Gauge Problem when the application
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Mechanical Vibration
Many studies have shown that vibration is the leading cause of pressure gauge failure in manufacturing plants. Vibration affects measurement accuracy in two ways. First of all, if the gauge is vibrating, the pointer on the dial will be challenging to read. Second, the gradual damage to the pointer mechanism due to vibration can eventually move the information from scratch, resulting in inaccurate readings.
What is the solution for mechanical vibration?
In most cases, a liquid-filled point is the most convenient and cheap way to protect the pressure gauge from vibration. The case filled with glycerin or silicone oil acts as a slow-moving damper. It also lubricates pinions and segment gears, reducing wear and extending gauge life.
The second solution is to move the meter away from the vibration source. NS? Use a capillary-connected diaphragm seal.
The diaphragm seal can be installed virtually anywhere in the application, and the line allows remote reading.
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Pulsation
Vibration represents the regular vibration of mechanical parts.
On the other hand, Pulsation is the usual cause of a sudden increase or decrease in pressure in the medium.
What is the solution for pulsations?
Like mechanical vibrations, liquid-filled housing is a simple solution—similarly, protective devices such as valves and outlet throttles.
This small device has a small opening for limiting and decelerating the pressure of the medium before hitting the pressure gauge. Chalk is cheap and easy to install.
Several pressure gauges for the pressure gas regulator are provided as standard, and the throttle is already screwed into the bore.
For more powerful pulsations, use a damper or needle valve. The snubber acts as a throttle but gives you more choices in materials, orifice sizes, and psi ratings.
In addition, thanks to the replaceable pistons or adjusting screws, the dampers are less clogged and easier to change in the field.
The needle valve also throttles the medium, reducing the effects of Pulsation. These pulsation attenuators are widely used in pump discharge and boiler house applications.
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High Temperatures
Different measuring devices have different tolerances for extreme temperatures.
Consider both the ambient temperature as seen in the Arctic Circle and near the furnace and the temperature of the process medium.
What is the solution to extreme temperatures?
Diaphragm seals with capillaries allow pressure measurements away from extreme ambient or medium temperatures.
The longer the run time, the more heat is dissipated before the pressure reaches the pressure gauge.
Install the cooling adapter. With ribs to increase the surface area, these adapters are very effective in radiating and dissipating heat.
Retrofitting with a thread connection is also very easy. Pigtails, coils, and mini siphons (rods and caps) use the same principle for heat dissipation.
Glycerin is a standard filler for pressure gauges.
Silicone oil is a better choice at very hot or cold ambient temperatures as it does not discolor over time due to heat or freeze at freezing temperatures.
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Pressure Peak
A pressure peak occurs when pressure rises sharply and then drops sharply.
This condition can cause all sorts of problems with meters that are not designed for this condition.
What is the solution for spikes?
As with Pulsation, a good solution for attenuating the effects of pressure peaks is to use a liquid-filled pressure gauge and accessories such as throttles, dampers, needle valves, diaphragm seals with capillaries.
Another way to avoid damage to the pointer and internal components is to replace the pressure gauge with an instrument in a higher pressure range.
As a rule of thumb, choose a pressure gauge that is twice the maximum expected pressure. Therefore, if the process typically reaches 500 psi, use a process that can be up to 1,000 psi.
To prevent the pressure gauge from exceeding a certain maximum, install overpressure protection on the device. This unique option allows the user to change the maximum pressure setting.
When the pressure reaches this level, the protector’s spring-loaded piston valve automatically closes to prevent pressure spikes on the gauge.
And when the system pressure drops about 25 ° below the preset maximum, the valve will reopen.
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Overpressure
This situation is similar to the peak pressure but occurs when the meter regularly measures pressure near or within the maximum range.
This condition is typically found in water and sewage treatments and gas pipelines.
Overpressure can cause the Bourdon tube to deform and tear. This is a major problem as breaks can allow corrosive media such as hydrofluoric acid (HF) in the alkylation unit to escape.
In pharmaceutical manufacturing, damage can ruin a costly product, leading to line shutdown, product quarantine, and process re-sterilization.
What is the solution to overpressure?
The solution also applies because overpressure is comparable to the pressure peak. Use a pressure gauge with a higher pressure range and install overpressure protection.
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Corrosion
Overpressure is similar to a pressure peak, so a solution also applies. Use a pressure gauge with a higher pressure range and install overpressure protection.
What is the solution to corrosion?
A diaphragm seal made of suitable corrosion-resistant material is used to isolate the measuring device from aggressive chemicals.
The diaphragm seal is available in a variety of standard and exotic alloys, both wet and non-wet. In addition, there is a differential material selection for diaphragm seals, such as 316L and 316Ti stainless steel sheets made of steel, Hastelloy, Monel, Inconel, Tantalum, and Titanium.
The metal can be left in place, lined with Teflon, or gold plated for added protection. When choosing the material for the diaphragm seal, pay attention to the material of the existing parts that are in contact with the medium.
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Clogging
Clogs are a problem for paper mills, sewage treatment plants, pharmaceuticals, and other industries. Sludge, sticky, viscous, grainy media can clog the system.
What is the solution for Clogging?
Again, a suitable diaphragm seal is used to separate the measuring device from complex media.