I have seen triple offset valves used for this very service. positive shutoff at -196°C and this coupled with weight/space savings can make ideal. As I saw no real mention of replacing actual valves on existing set-up, I guessed you are changing it at design stage.
Zwick are good, so are...
what type of valve are you looking at solving the problem on, where will the gasket be, will it be full dymanic function, static or semi-static & what is service liquid...
Pure graphite with internal armour are used on triple offset butterfly valves (between disc & sealing ring).
If you can...
Wafer valves are "held in place" between two flanges, a lugged valve is bolted onto line flanges through threaded holes in lugs (can be between two flanges, or end of line).
A flanged valve is assembled on to line through nuts & bolts, valve flanges have through holes, not threaded (can also be...
Forgot to mention that threaded bar + 2 nuts costs much less than bolts, and are easier to use for pre-tensioning of bolts (use of e.g. Hydrotight equipment), this last point also answers you query as to why they are so long.
Ciao,
You could argue that thermal expansion of unprotected threaded bar/partially threaded bolt (normal as long bolts tend to be either threaded bar + 2 nuts, or long bolts, partially threaded + 1 nut) is far greater than a shorter bolt.
Obviously thermal expansion of a component that is keeping a...
Use a manual gearbox operation, the position transmitter mounted on top (as for a actuator) will give local visual indication and transmit position to remote control room.
Try contacting flowbus www.flowbus.com (actuator and gearbox manufacturer) for fast delivery & good understanding of your...
gerhardl is right, too many factors to pinpoint the cause of your problems.
My suggestion would be "as a starter" to check exactly where the leakage occurs, if it is always the same point/component that gives leakage.
Are the components visibly damaged/deformed when valve is disassembled for...
for sizes of 1/4" & below I would suggest direct acting solenoid operated valve, no need for a pneumatic actuator to rotate a ball valve, this is space & energy consuming.
Have a look at ITT http://www.ittaerospace.com/scripts/products/index.asp?p=valves
Ciao,
Be aware that a offset butterfly valve in preferred direction has a BTO (break to open) torque higher than TSO torque, the opposite applies when offset valve is in non-preferred direction (higher to seat/seal & lower to unseat/open).
Ciao,
Most swing check valve manufacturers market up-to 36", however, Bray do have this http://www.bray.com/docs/brochures/R-3001_EN_V31_2008-11.pdf
Hope this solves the problem, or at least points you in the right direction.
Ciao,
Does it necessarily have to be swing check ?
Standard swing check valves for this size in wafer comfiguration (or short bodies) will be difficult to source, of course, if you pay enough, you will find someone willing to make it for you (dont know about lead times though).
Possible options are...
rneil is right,
call your supplier and ask for torque requirements for valve in its actual direction, if they supplied valve complete with actuator, they can advise if the set-up will fuction correctly. If they advise a torque requirement above that of actuator output, contact actuator...
Stadnard ISO 15364:2007 deals with P/V valves.
However, if your supplier no longer exists, I would seriously consider getting a new one, gudging by the pressure range, you should have no problems in sourcing these & save costs of testing a valve that only you can certify is working corrdectly.
Ciao,
My suggestion, based on past experience is to keep with original spec, the reason for RPTFE could be pressure (#1500 is fairly high) causing extrusion of seat material, temperature limits....or combination(higher temp-lower pressure OR lower temp-higher pressure).
Lots of products on the market...
I admit I am no expert on these, but I would have thought you originally had a problem in flow...not pressure, you could try a higher flow capacity pressure reducer, keeping your zero & still achieving speeds required.
Increasing pressure tends to have negative effects on many types of...
Concentric butterfly valves are inherently "dry-shaft" as the seat itself should seal against shaft as well as disc.
of course, the possibility of a malfunction exists, but that is always the case regardless of valve design.
Ciao,
