How Do You Repair A Stainless Steel Fluid Filled Pressure Gauge

Pressure level gauge failure can be attributed to one or more of these 8 reasons: mechanical vibration, pulsation, extreme temperature, pressure level spikes, overpressure, corrosion, bottleneck, and mishandling/abuse.

Pressure gauges are an integral function of an application'due south warning organization. By constantly measuring force per unit area, these instruments let users to come across how a process is doing. Gauges are sturdy and can handle challenging atmospheric condition. However, even the toughest instruments will feel failure if they weren't designed for a specific awarding or status.

At WIKA Us, our customers often ask us why their gauges are damaged or stopped working properly. With decades of force per unit area experience, we take seen all the causes of pressure level gauge failure.

diagram of a Bourdon tube pressure estimate

How A Pressure Gauge Works

Before getting into why things become wrong and how to troubleshoot the problem, information technology's important to first empathize the inner workings of a mechanical approximate, the virtually popular of which is the Bourdon tube pressure gauge.

The Bourdon tube is a hollow C-shaped bound chemical element inside the case. Equally the tube is pressurized from the media inbound it, information technology starts to movement – similar a balloon trying to equalize. This move is translated through the connecting link, attached to the Bourdon tube via the end slice, into a pressure measurement that the arrow indicates on the dial.

8 Causes of Gauges Failure

When a pressure gauge doesn't piece of work as expected, the crusade can be traced back to at least ane of these eight reasons:

one. Mechanical vibration

Numerous studies have shown that vibration is the primary crusade of pressure gauge failure in manufacturing facilities. Vibration has a negative impact on gauge accurateness in two means. Beginning, information technology is difficult to read the pointer on a dial when a judge is vibrating. Second, incremental damage to the pointer mechanism from vibration tin somewhen move a arrow off naught, producing inaccurate readings.

Visible signs of mechanical vibration

• Metal filings/grit, like a halo, inside the gauge window from worn pinion and segments gears
• Detached arrow if the vibration is severe

(left) halo within gauge window; (right) detached pointer

Risks posed by mechanical vibration

• Wearable and tear of internal components
• Loss of accuracy/functionality
• Pressure organization failure

(left and middle) worn pinion gears; (right) worn segment gear

model 990.28 diaphragm seal

Solutions for gauges experiencing mechanical vibration

For most situations, a liquid-filled case is the most user-friendly and toll-effective way to protect pressure gauges from vibration. The glycerin or silicone-oil instance fill acts as a damper to slow down the movement. It likewise lubricates the pinion and segment gears, thereby reducing wear and prolonging the life of a gauge.

A second solution is to move the gauge away from the source of the vibration. How? Use a diaphragm seal with capillary connection, like the 990.28 prison cell-blazon (sandwich) seal. A diaphragm seal can be mounted practically anywhere in the application, and the line allows for remote reading. (Run into this video and blog for more than info on how diaphragm seals piece of work.)

ii. Pulsation

pointer flutter

Vibration refers to regular oscillation of mechanical parts. Pulsation, on the other hand, is regular instances of rapid pressure increases and decreases of the media.

Visible signs of pulsation

• Arrow flutter
• Loose or cleaved arrow in extreme cases

Risks posed by pulsation

• Difficulty in obtaining an accurate reading
• Wearable and tear of internal components
• Loss of accuracy/functionality
• Pressure organization failure

(left) snubber; (right) socket restrictor

Solutions for gauges experiencing pulsation

Equally with mechanical vibration, a liquid-filled case is an piece of cake solution. So are valves and protective devices like a socket restrictor. This small device has a minor orifice to restrict and slow downwardly the pressure of the media before it encounters the gauge. Restrictors are cost-effective and easy to install. Several gauges, like model 111.eleven for compressed gas regulators, come standard with a restrictor already threaded into the diameter.

For more than extreme pulsation, employ a snubber or needle valve. Snubbers function like restrictors but come in more material choices, orifice sizes, and psi ratings. Snubbers are also less prone to bottleneck and are more than adjustable in the field, thanks to interchangeable pistons or aligning screws. Needle valves too throttle the media, thereby reducing the bear on of pulsations. These pulsation dampeners are normally establish in pump discharge and banality house applications.

3. Extreme temperature

Different gauges take different tolerances for farthermost temperatures. We look at both ambience temperatures, such every bit what is found in the Chill or around a furnace, and the temperature of the process media.

gauge discoloration

Visible signs of extreme temperature

• Dial and/or liquid fill up is discolored, usually yellow, orange, brown, or black
• Dial, example, or window is melted – normally because the media is too hot

Risks posed by farthermost temperature

• Difficulty in obtaining an accurate reading
• Loss of accuracy/functionality
• Force per unit area system failure

Solutions for gauges in extreme temperatures

model 910.32.250 mini cooling adapter

A diaphragm seal with capillary allows force per unit area measurement to occur abroad from extreme ambient or media temperatures. The longer the run, the more heat is dissipated before the pressure reaches the gauge. Or attach a cooling adapter like the 910.32.200 (upwardly to 500°F/260°C) or 910.32.250 (up to 700°F/370°C). With fins to increase the surface area, these adapters are very effective at radiating and dissipating heat. They're also extremely easy to retrofit using threaded connections. Pigtail, coil, and mini (rod and cap) siphons use the same principle to dissipate heat.

Glycerin is the typical fill fluid for pressure gauges. For extremely hot or cold ambient temperatures, silicone oil is the better choice every bit it will non discolor in heat over time or freeze in sub-zero environments.

4. Pressure spikes

Spikes occur when the force per unit area sharply increases and then of a sudden drops. This condition tin can cause all sorts of bug for gauges not designed for this condition.

bent pointer

Visible signs of pressure level spikes

• Aptitude arrow, like a fishtail or fish hook, from hitting the end pivot likewise often
• Nicked or broken pointer from hitting the stop pin too hard
• Broken finish pin

Risks posed by force per unit area spikes

• Increased clothing on movement and components
• Loss of accuracy/functionality
• Split Bourdon tube, leading to released media
• Pressure organization failure

Solutions for gauges experiencing pressure level spikes

Equally with pulsation, practiced solutions for dampening the effects of force per unit area spikes are to employ a liquid-filled gauge and/or accessories similar restrictors, snubbers, needle valves, or diaphragm seal with capillary. Another manner to prevent damaged pointers and internals is to supercede the estimate with one that has a college pressure level range. A good rule of thumb is to cull a gauge that is two times the expected pressure maximum. And then, if a process typically reaches 500 psi, apply one that goes up to 1,000 psi.

For greater reassurance that a gauge never exceeds a certain maximum, attach an overpressure protector to the instrument. This unique option allows the user to changing the maximum pressure setting. If the pressure ever reaches that value, the protector'south jump-loaded piston valve will automatically shut, preventing the gauge from experiencing the spike. And when the system pressure drops approximately 25% below pre-prepare maximum, the valve with automatically reopen.

5. Overpressure

pointer buried against stop pin

This situation is very like to pressure spikes, but occurs when the approximate regularly measures pressures near or at the maximum range. Nosotros typically encounter this condition in h2o/wastewater handling and gas lines.

Overpressure can cause the Bourdon tube to deform and divide. This is major problem because a rupture allows caustic media, such as the hydrofluoric (HF) acid in alkylation units, to escape. In pharmaceutical manufacturing, a rupture event ruins very expensive product and leads to shutting downward the line, quarantining the production, and re-sterilizing the process.

Visible signs of overpressure

• Arrow buried against stop pin
• Pointer dislodges terminate pin

Risks posed past overpressure

• Increased wearable on move and components

• 

  model 910.xiii overpressure protector

  Loss of accuracy/functionality
• Carve up Bourdon tube, leading to released media
• Pressure level system failure

Solutions for gauges experiencing overpressure

As overpressure is similar to pressure spikes, so is the set up: employ a gauge with a college pressure level range, and attach an overpressure protector.

6. Corrosion

corroded pressure guess

Many industries work with harsh chemicals: hydrofluoric acid in refineries, flocculants and chlorine in wastewater treatment, chlorinated gases in fiber optic production, and so on. These media discover their way into gauges.

Visible sign of corrosion

• Discoloration and deterioration of the gauge case, pointer, connectedness, and dial

Risks posed by corrosion

• Loss of accuracy/functionality
• Pressure system failure

Solutions for gauges in corrosive environments

Isolate the estimate from harsh chemicals past using a diaphragm seal fabricated of the appropriate corrosion-resistant materials. WIKA'due south diaphragm seals come in a multifariousness of standard and exotic alloys for both the wetted and non-wetted parts: 316L and 316 TI stainless steels, Hastelloy^®, Monel^®, Inconel^®, tantalum, and titanium. The metals can be left as-is or, for extra protection, lined with Teflon® or plated with golden. When deciding on the materials for your diaphragm seals, look at what the existing wetted parts are made of, and choose those.

chock-full pressure gauge

7. Clogging

Bottleneck is an event for paper plants, wastewater plants, pharmaceuticals, and other industries, equally slurry, pulpy, viscous, and high-particulate media can gum up the system.

Visible sign of bottleneck

• Gauge at or about zilch when the system is operating

Risks posed by clogging

• Loss of accuracy/functionality
• Possibility of overpressure

Solutions for gauges measuring clogging media

Again, use a diaphragm seal to divide the gauge from the challenging media. An splendid solution is WIKA's All-Welded System (AWS), an associates comprising an XSEL^® industrial process estimate permanently welded to a bell-shaped diaphragm seal.

As the AWS nevertheless has a pocket-sized orifice that the media can enter, customers can opt for versions with a flushing port. This component allows operators to clear away media either when clogging occurs or during regular maintenance.

Another solution is WIKA'south INLINE™ diaphragm seals, which has smooth walls for full flow-through. By eliminating dead spaces, there's no take a chance of media buildup.

8. Mishandling/abuse

Gauges look sturdy, particularly the larger procedure gauges, but they are not designed to exist handles or footholds! During site visits, we often see bear witness of gauge mistreatment. Operators might take hold of on to a judge as they movement around process skids on wheels, or step on them equally they climb scaffolding. Not just is this practice unsafe, it increases the chances of gauge damage and failure.

pressure level gauges with cleaved window (left) and cracked example (right)

Visible signs of mishandling/abuse

• Cracked case
• Broken window
• Loss of instance filling
• Crooked or bent gauge and/or process connection

Risks posed by mishandling/abuse

• Loss of functionality

Solutions for guess mishandling/abuse

Training is the best prevention. Employees should be aware of the dangers of mishandling gauges. They should as well know how to properly connect gauges. For example, when threading the gauge onto the process, some people tighten it by manus, which risks torquing the case. When the NPT or Chiliad connectedness has a wrench flat area, use a wrench to tighten the gauge.

WIKA United states's pressure specialists accept decades of experience diagnosing why gauges fail, and so coming upward with solutions so that instruments last longer. When the causes aren't obvious, we encourage customers to take reward of our Musical instrument Failure Analysis (IFA) plan. Transport the failed gauge to our facilities in Lawrenceville, Georgia, and our engineers will deport a total evaluation on the nonfunctioning approximate – all free of charge. Contact WIKA United states of america for more information about why pressure gauges neglect and what yous can do to solve the problem.

Source: https://blog.wika.us/knowhow/8-common-reasons-for-pressure-gauge-failure/

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