Interview Questions.

Question 1. What Is A Pressure Relief Valve?

Answer :

Relief valves are automatic valves used on system lines and device to prevent over pressurization. Most comfort valves honestly elevate (open) at a preset stress and reset (shut) whilst stress drops only slightly beneath the lifting pressure.

System pressure clearly acts below the valve disk on the inlet of the valve.

When gadget pressure exceeds the force exerted by way of the valve spring, the valve disk lifts off its seat, permitting a number of the system fluid to break out through the valve outlet till machine strain is reduced to simply under the relaxation set factor of the valve. The spring then reseats the valve.

Question 2. What Is The Difference Between Orifice And Inlet Size?

Answer :

The orifice diameter is the internal beginning of the valve and is used to calculate the go with the flow capacity of the valve. It’s the inner hole. The inlet size is the interface or the size/kind of the threads where you attach the valve. As of e-book Kingston Valves do no longer come in metric sizes, best NPT (National Pipe Thread).

Question three. What If My Pressure Regulator Is Leaking Or Not Working Properly?

Answer :

Leaking may additionally arise because of debris getting under the diaphragm and stopping it from seating properly and creating gaps which lets in air to skip. This may be due to having a dirty air surroundings or via having insufficient filtration. You ought to first check the regulator to ensure that the diaphragm is easy and undamaged. You must additionally make certain which you have an ok filter out upstream and then recollect changing the filter detail. Dirty air and debris within the gadget can also cause the diaphragm to tear in which case you would revel in the same overall performance problems. The diaphragm may be effortlessly changed by means of shopping a restore package.

Question 4. Is There A Difference In The Definition Of “set Pressure” Between Air & Liquid Applications?

Answer :

Yes. Liquid Applications: Liquids tend to be incompressible, which means they cannot be compressed like air. Liquids can be underneath stress but as quickly as the quantity adjustments they at once lose all strain (strain goes to 0). There are 3 general definition inside the industry for liquid packages. They are: start to leak, first regular movement and complete glide. For Liquid applications – Kingston defines “Set Pressure” as the first constant movement of flow out of the valve.

Question five. Why Is My Valve Leaking?

Answer :

It is everyday for spring-operated protection valves to showcase leakage or simmer/warn, because the running stress procedures the nameplate set stress, commonly in the 80%-90% variety of nameplate set strain. The ASME Boiler and Pressure Vessel Code does now not require a particular seat tightness requirement. A certain level of leakage is permitted according to producers’ published literature. Kingston defines seat tightness requirements as follows: Factory Standard Seat Tightness Performance: o Hard Seat Valves – no audible leakage at 20% under nameplate set. O Soft Seat Valves – no audible leakage at 10% underneath nameplate set. At very low set pressures (20 psi and beneath), the ratio of the downward spring pressure as compared to the upward pressure force could be very small. In those instances it may be not possible to acquire seat tightness. Use smooth seat valves for advanced seat tightness in applications which fall within the soft seat material temperature barriers. Although soft seat valves will commonly provide a higher degree of seat tightness than metal seats, Factory Standard does now not make sure bubble-tight seats, irrespective of seat cloth.

Question 6. What Set Pressure Should The Valve Is Set To Open?

Answer :

Typically, the valve must be nameplate set to open at the MAWP (Maximum Allowable Working Pressure) of the vessel the valve is supposed to guard. There is a tolerance to real set stress, which means that a valve set at a hundred psig nameplate may also open slightly above or beneath a hundred psig. Consult the contemporary ASME Boiler and Pressure Vessel Code for tolerance instructions and unique situations while the set strain may be distinct than the MAWP.

Question 7. What Is The Blow Down Of A Section Viii Or Non-code Safety Valve?

Answer :

The ASME Boiler and Pressure Vessel Code does not have blow down necessities for Section VIII (or non-code) valves. Blow down can also vary from less than 2% to extra than 50%, relying on many elements consisting of; valve layout, dimensional tolerance variation, in which the set pressure falls inside the set pressure range of a spring, spring rate/force ratio, warn ring/manual settings, etc. Typical blow down for maximum valves is 15% to 30%, but cannot be guaranteed.

Question 8. How Does Back Pressure Affect Valve Set Pressure And Capacity?

Answer :

Back stress reduces set stress on a one-to-one foundation, i.E., a valve set at a hundred psig subjected to a backpressure at the outlet of 10 psig will no longer actuate till system pressure reaches a hundred and ten psig. Back strain substantially reduces capacity; typically backpressure of 10% of set strain will lower capacity by means of 50%. Specific potential discount should be decided via the person on a case-by using-case foundation via go with the flow checking out. Back stress in extra of 10% of set strain isn't endorsed.

Question nine. Does Altitude Affect Set Pressure?

Answer :

No. Gage stress (psig) is used to set valves so the consequences of weather and altitude on set strain can be not noted.

Question 10. Why Does My Valve Actuate/open Early?

Answer :

It might not be. Warn/simmer or seat leakage is on occasion fallacious for set strain. Visible or audible leakage or device pressure drop isn't always set stress. The accurate definition of set stress is:For liquid service, first vertical consistent flow. For liquid carrier, first vertical steady flow. For some valves in air/gas provider, First audible. Variance of set stress is allowed, i.E., a Section VIII air valve with a nameplate of a hundred psig set strain may additionally open from ninety seven psig to 103 psig, however will be manufacturing facility set around 102 psig.

Question 11. How High Can My System Pressure Be Before My Valve Opens?

Answer :

Maintain a minimum operating gap of 10% among the system operating pressure and the protection valve nameplate set pressure. Since direct spring operated safety valves might also “Simmer” or “Warn” at 90% of the nameplate set strain, and for the reason that manufacturing facility general leak check done at eighty% of nameplate set strain, higher seat tightness performance may be anticipated with an running hole of 20%.

Question 12. Which End Should Be Connected For Vacuum Valves?

Answer :

This is often a confusing topic. The correct installation frequently looks backwards from what appears to be accurate. A paper guidance tag illustrating the proper connection is hooked up to each valve. Vacuum valves should have the NPT threads which might be cast essential to the body connected to the vacuum source. See the meeting drawing for extra explanation.

Question thirteen. Why Is There A Hole In The Valve Body?

Answer :

This drain hole is required on some fashions with the aid of the ASME Boiler and Pressure Vessel Code. It is intended to prevent any condensate from amassing within the body which can freeze or corrode internal valve parts and prevent the valve from beginning. The drain hollow need to be piped away to soundly eliminate any discharge or condensate.

Question 14. What Mounting Orientation Should Be Used To Install A Safety Valve?

Answer :

Installing a safety valve in any position aside from with the spindle vertical and upright can also adversely affect performance and lifetime and won't meet code. Installation in any role aside from vertical can violate code requirements.

Question 15. How Often Should I Test/look into My Valve?

Answer :

Maintenance must be achieved on a normal foundation. An initial inspection c language of no longer than 12 months is usually recommended. The user should establish the appropriate inspection c language relying on the carrier situations, the situation of the valve and the level of performance desired.

The ASME Boiler and Pressure Vessel Code do no longer require nor cope with testing established valves. The only aspect the codes states are design and set up necessities, together with some valves need to have a lifting lever. For example for segment VIII:

“Each pressure remedy valve on air, water over 140F, or steam service shall have a big lifting tool which when activated will release the seating pressure at the disk when the pressure relief valve is subjected to a stress of at the least seventy five% of the set pressure of the valve.

Question 16. Is The Proper Way To Install A Safety Or Safety-comfort Valve?

Answer :

Safety and safety-remedy valves need to be hooked up vertically with the drain holes open or piped to a handy area. All piping should be absolutely supported.