Manual Diaphragm Valves
Manual diaphragm valves remain the most common isolation point on a specialty gas panel. A quarter-turn or multi-turn handwheel drives a metal diaphragm onto the seat, giving a leak-tight shut-off with no sliding seal in the gas path.
Valonix manual valves are used at cylinder connections, regulator inlets, point-of-use tool isolations and maintenance bypasses. Where a line is only operated during service or changeover, a manual valve is simpler, cheaper and easier to validate than an actuated one.
Handwheel control and seat life
A controlled closing torque extends diaphragm life. Over-torquing is the most common cause of premature seat damage in high purity valves, so specify a torque-limiting handwheel or train operators on the recommended closing torque rather than tightening until it feels tight.
- Controlled closing torque for long diaphragm life
- Clear open/closed indication
- No packing adjustment or repacking required
Low pressure and high pressure variants
Low pressure versions rated around 300 PSI cover most tool hook-up and distribution lines after the regulator. High pressure versions rated 3000-4500 PSI sit upstream of the regulator at the cylinder or tube trailer connection. Both share the same diaphragm sealing principle.
- 300 PSI class for post-regulator distribution
- 3000-4500 PSI class for cylinder side
- Same port and panel footprint across the family
When to choose manual over pneumatic
Choose manual isolation where the valve is not part of an interlock sequence, where the panel has no instrument air, or where a lockable maintenance isolation point is required. Choose pneumatic when the valve must close on an alarm, a purge step or a tool recipe transition.
- No instrument air required
- Ideal for lockable maintenance isolation
- Lower cost for non-sequenced lines
Valves in this category
VX4-LPVX4 Low Pressure UHP Diaphragm Valve
- Port size1/4, 3/8
- Max. pressure300 PSI
- Cv0.27
VX4H-HPVX4H High Pressure Diaphragm Valve
- Port size1/4
- Max. pressure4500 PSI
- Cv0.20
VX8-LPVX8 Low Pressure UHP Diaphragm Valve
- Port size1/2
- Max. pressure300 PSI
- Cv0.70
VX8H-HPVX8H High Pressure Diaphragm Valve
- Port size1/2
- Max. pressure3500 PSI
- Cv0.80
Typical specifications
| Actuation | Manual handwheel / knob |
|---|---|
| Pressure range | 300 PSI standard, up to 4500 PSI HP |
| Port sizes | 1/4", 3/8", 1/2", 3/4", 1" |
| End connections | VCR, butt weld, compression |
| Body | 316L VIM/VAR stainless steel |
| Options | Lockable handle, panel mount |
Frequently Asked Questions
How tight should a manual diaphragm valve be closed?
Use the recommended closing torque. Over-torquing deforms the seat and shortens diaphragm life; a torque-limiting handwheel helps.
Do manual valves need packing maintenance?
No. The metal diaphragm isolates the stem, so there is no packing to adjust or replace.
Can manual valves be panel mounted?
Yes. Panel-mount versions with a consistent face-seal envelope are available for gas cabinets and VMB panels.