Pressure gauge is used to monitor the pressure inside a system or process. When a gauge is not appropriately maintained, it can fail to function properly and lead to inaccurate readings.
Mechanical Vibration
Vibration is the leading cause of pressure gauge failure in manufacturing facilities. Vibration harms gauge accuracy in two ways: First, it is difficult to read the pointer on a dial when a gauge is vibrating. Second, cumulative damage to the pointer mechanism from vibration can eventually move a pointer off zero, producing inaccurate readings.
Numerous studies have shown that vibration is the leading cause of pressure gauge failure in manufacturing facilities. Vibration damages the components of a gauge’s internal mechanism, which can cause erratic readings and decreased accuracy over time as parts wear away or become damaged by vibration exposure.
Solution
In most situations, a liquid-filled enclosure is the most practical and economical way to protect the gauges from vibration. The glycerin or silicone-oil case fill is a damper to slow the movement. It also lubricates the pinion and gear segments, reducing wear and extending the life of a caliper.
A second solution is to move the gauge away from the vibration source. How? Use a membrane separator with a capillary connection. The sealed capillary will dampen any vibrations transferred from one to another. A diaphragm seal can be mounted virtually anywhere in the application, and the line allows for remote reading. The bar is compatible with many devices, including all types of sensors, strain gauges, and pressure transducers. Line lengths are available in several standard sizes measured in feet or meters. The line can be installed with simple hand tools such as a wrench and screwdriver.
Pulsation
Pulsation is the regular oscillation of mechanical parts. It refers to the rapid pressure increases and decreases in a medium.
Vibration, on the other hand, is an instance of rapid pressure increases and decreases in a medium.
Solution
Regarding mainsprings, there are three main options for regulating pressure: a liquid-filled case, a valve and protective device like a socket restrictor, or a piston/adjustment screw combination.
The first two methods are easy to install and cost-effective. Both come pre-installed with a small orifice that restricts and slows down the pressure of the media before it encounters the gauge. Restrictors are also less prone to clogging, so they’re more adjustable in the field than snubbers.
For compressed gas regulators, several gauges come standard with a restrictor already threaded into the bore. These gauges usually have an adjustable piston or adjustment screw to accommodate different sizes of orifices and other pressures. For more intense pulsations, use a damper or a needle valve. Snubbers function like restrictors but come in more material choices (like stainless steel), size choices (from small or more significant), and psi ratings (from low to high).
Snubbers are also less prone to clogging, thanks to interchangeable pistons or adjustment screws; all you need is work for your application!
Needle valves are commonly used in pump discharge and boiler house applications. These valves have a unique design that makes them very effective in reducing the impact of pulsations. A needle valve has a needle-like opening that allows water to flow through it at a controlled rate. In addition, the needle valve is usually connected to other components such as a pipe, tank, or boiler, which helps to regulate water flow through these systems.
Extreme Temperatures
The temperature of the process media can have a significant effect on your gauges. That’s why we take extreme temperatures into account when designing our gauges.
We have different tolerances for different areas so that you can choose the gauge that best fits your needs in any given situation.
Solutions
When it comes to pressure gauges, choosing the suitable fluid for your application is a big decision.
A diaphragm seal with capillary allows pressure measurement away from extreme ambient or media temperatures. The longer the stroke, the more heat is dissipated before the pressure reaches the gauge. Or connect a cooling adapter. These adapters effectively radiate and dissipate heat with fins to increase the surface area. They’re also straightforward to retrofit using threaded connections. Pigtail, coil, and mini (rod and cap) siphon use the same principle to dissipate heat. Glycerin is the typical filling liquid for manometers. However, silicone oil is better for extremely hot or cold ambient temperatures as it will not discolor in heat over time or freeze in sub-zero environments.
Pressure Spikes
Pressure spikes can cause many problems for gauges not designed for this condition.
The gauge’s needle may jump or skip several times when pressure spikes occur. This can cause confusion and frustration for the user, who will no doubt be wondering what’s happening with their readings.
In addition, pressure spikes can cause other issues for your gauge: An increase in pressure can trigger an unwanted alarm that sounds when the pressure drops. A sudden pressure drop can damage the mechanism inside the gauge itself.
Solution
One of the biggest challenges most manufacturers face is dealing with pressure spikes. Whether it’s a pulsation problem or just a need for greater accuracy and consistency, you can beat the reliability of a liquid-filled gauge.
An excellent solution to dampen the effects of pressure spikes is to use a liquid-filled gauge or accessories like restrictors, snubbers, needle valves, or diaphragm seals with capillary.
Another way to prevent damage to pointers and internal components is to replace the pressure gauge with one with a higher pressure range.
A good rule of thumb is choosing a gauge two times the expected pressure maximum. So, if a process typically reaches 500 psi, use one up to 1,000 psi.
Attach an overpressure protector to the instrument for reassurance that a gauge never exceeds a certain maximum. This unique option allows the user to change the maximum pressure setting.
The protector’s spring-loaded piston valve will automatically close if the pressure reaches that value.
Overpressure
Pressure spikes are very similar to pressure surges, but they occur when the gauge regularly measures pressures near or at the maximum range.
Pressure spikes can cause the Bourdon tube to deform and split. This is a significant problem because a rupture allows acidic media, such as the hydrofluoric (HF) acid in alkylation units to escape. In pharmaceutical manufacturing, a rupture event ruins an expensive product and leads to shutting down the line, quarantining the product, and re-sterilizing the process.
In water/wastewater treatment and gas lines, pressure spikes can damage pipes or other components that are under pressure. For example, an exposed pipeline pressurized with water or air in an area with high temperatures (like an oven) could crack or even explode!
Solution
If you’re looking to avoid overpressure, you should install an overpressure protector. Overpressure is similar to pressure spikes, so the solution is to use a gauge with a higher pressure range and attach an overpressure protector.
Corrosion
The corrosion of the pressure gauge is a common problem that can affect any gas or liquid supply. The leading cause of this problem is contamination, which can be caused by dirt and even water. In addition, people who work in the field may also cause damage to the pressure gauge if they are not careful while using it.
Solution
If you want to isolate your gauge from harsh chemicals, consider using a diaphragm seal made of corrosion-resistant materials. The standard materials include 316L and 316 Ti stainless steel, Hastelloy and Monel, Inconel, and tantalum.
The metals can be left as-is, lined with Teflon, or plated with gold.
Clogging
Clogging is a massive problem for paper plants, wastewater plants, pharmaceuticals, and other industries. These industries use a wide range of media to get their work done, but these materials can cause clogging if not appropriately managed.
For example, paper plants use slurry as part of their processes. The slurry is a liquid waste product from the pulping process that contains cellulose fibers, lignin, and other pulp solids. If slurry has been allowed to sit for too long before being treated or if it’s allowed to accumulate in one place for too long, then it can clog the system by blocking pipes or becoming embedded in the walls of pipes themselves.
Solution
The diaphragm seal is a simple and effective way to separate the gauge from the challenging media.