WIKA FAQ

Q:When should a diaphragm seal be used with a pressure gauge?

A:Because the sensing element of a pressure gauge may be exposed directly to the measured medium, consider the characteristics of this medium. It may be corrosive, it may solidify at various temperatures, or it may contain solids that will leave deposits inside the sensing element. For pressure fluids that will not solidify under normal conditions or leave deposits, a Bourdon tube gauge is acceptable. Otherwise a SealGauge® or diaphragm seal should be applied.

Q:How do I choose the right liquid for a filled gauge?

A:The type of liquid used to fill the gauge varies with the application. Although pure glycerine provides the best performance in most applications, each has its own requirements. Guidelines to help ensure that a fluid is properly matched to an application are:

1. If icing is a problem, use gauges filled with silicone oil or other comparable liquids - they have low viscosities even at -60°C.
   
2. If the system has electric accessories, such as contacts, use insulating oils.
   
3. If extreme temperature fluctuations are expected, use silicone oils. The higher the liquid viscosity, the greater its dampening capacity. The reason for this is that dampening changes in proportion to the temperature-dependent viscosity of the filling liquid. The suitable degree of dampening depends on the operating requirements the gauge must meet, such as pointer response time, pressure extremes, vibration and changes in pressure. WIKA can recommend specific liquids to suit problem applications.
   

Q:How do I vent a liquid-filled gauge?

A:To vent a WIKA liquid-filled gauge, move the valve to the open position which will release any pressure or vacuum built up in the case. If the gauge is installed in an upright position, the lever can be left in the open position (the lever allows use of the gauge in a non-upright position).

Q:What are the advantages of a liquid filled gauge?

A:Liquid-filled pressure gauges provide a number of advantages:

1. The liquid absorbs vibration and pressure spikes.


2. The dampening action of the liquid enables the operator to take reading during conditions of rapid dynamic loading and vibration.


3. The liquid lubricates all moving elements, dramatically reducing wear in the movement.


4. Because most liquid-filled gauges are filled with non-aqueous liquid and hermetically sealed, they perform in corrosive environments and are immune to moisture penetration and icing.

Q:What if my applications encounter severe pressure fluctuation or pulsation?

A:In applications involving severe pressure fluctuation or pulsation, the use of restrictors and/or snubbers is recommended. In addition, liquid-filled gauges increase the service life of gauges in these conditions. WIKA liquid-filled gauges are generally filled with glycerine. Silicone (for greater temperature extremes) and Halocarbon® (for use with oxidizing agents such as chlorine, oxygen, and hydrogen peroxide) are also available.

Q:What if my connections are atypical?

A:Radial (LM) and back (CBM or LBM) connections are available for most WIKA gauges. WIKA stocks gauges with standard NPT threaded connections. Other types such as metric threads, straight threads, hose barbs, and special fittings are available as a special order. Pressure gauges should be mounted in the upright position. For applications where the gauge is mounted sideways, horizontal, or upside down, contact WIKA Customer Service for gauge type compatibility.

Q:What is normal ambient pressure for WIKA gauges?

A:Please refer to the table below.

Q:What is WIKA accuracy for pressure gauges?

A:WIKA stocks gauges with accuracies of ± 3/2/3% to ± 0.1% of span (ASME Grade B to Grade 4A). Generally, the more accurate gauges are larger and more costly.

Q:What pressure range should I work in?

A:A gauge range of twice the working pressure is generally selected. The working pressure in all cases should be limited to 75% of the gauge range. Where alternative pressure and pulsation are encountered, working pressure should be limited to 2/3 of the gauge range.

Q:When is liquid-filled gauge case venting necessary?

A:For pressure gauges with full-scale ranges of 300 PSI and below (including vacuum and compound ranges of 30° HG-0-200 PSI and below), case venting (after the gauge is installed) is necessary to preserve the accuracy. Temperature fluctuations during shipment and in the process application cause the liquid filling to expand and contract which, in turn, increases or decreased case pressure. As a result, accuracy can be decreased and the pointer may not return to zero properly until the gauge is vented to the atmosphere.

Q:Can I get TRONIC product prices and delivery estimates online?

A:This information is not currently available online. Please contact TRONIC Customer Service for this information.

Q:How do "Intrinsically Safe" and "Explosion-Proof" transmitters differ?

A:Instrinsically safe transmitters, by their design, limit the thermal and electrical energy to a point where ignition is not possible. In contrast, explosion-proof transmitters work on the principle of containment, where the transmitter is enclosed in a housing that is designed to contain, control, cool and then vent any possible explosion. This is accomplished by specially designed flanges, or more commonly, with threaded joints. The hot gases must travel a specific distance along the threads before they are cool enough to be safe. Care must be taken to avoid cross-threading the joints during assembly. In addition, heavy conduit and seal-offs are required to maintain an explosion-proof system.

Q:What is the difference between a “Transmitter” and a “Transducer”?

A:A pressure transmitter converts applied pressure to an amplified output such as 4-20 mA or 0-10 V. A pressure transducer converts applied pressure to an unamplified signal such as 2mV/V.

Q:What is the TRONIC return policy?

A:Special order items are not returnable. To return standard items, fill out the RMA form or contact the RMA department at 888-945-2872 ext. 4013.