Metering & Needle Valves
Metering and needle valves set a controlled, repeatable flow rather than simply opening or closing a line. Valonix high purity metering valves are used on carrier gas feeds, calibration lines, analyser sample loops and dopant gas dilution skids.
Two flow characteristics are available: a fine metering characteristic with Cv around 0.019 for very low flows, and a regulating characteristic around Cv 0.30 for general flow setting at up to 700 PSI.
Metering versus regulating stems
A metering stem has a fine taper and a long travel, giving high resolution at low flow. A regulating stem opens faster and suits higher flows where fine adjustment is less critical. Choosing the wrong stem makes a loop hard to tune and can cause an analyser to drift.
- Metering stem: Cv 0.019, fine low-flow resolution
- Regulating stem: Cv 0.30, general flow setting
- Match stem to the required control range
Connections and pressure
Ports cover 1/4 in, 1/2 in and 6 mm tube with VCR face seal, butt weld, compression or socket weld ends. Maximum working pressure is 700 PSI. For UHP service, face-seal or welded ends keep the number of threaded cavities in the gas path to a minimum.
- 1/4, 1/2 in and 6 mm ports
- VCR, butt weld, compression, socket weld
- 700 PSI maximum working pressure
Typical applications
Common duties include setting carrier and purge flows on gas chromatographs, controlling dopant dilution on diffusion tools and trimming calibration gas to an analyser. Pair the valve with a check valve on the downstream side where reverse migration is a concern.
- Analyser and GC carrier gas
- Calibration and sample loops
- Dopant dilution and purge trimming
Valves in this category
VMUVMU High Purity Metering Valve
- Port size1/4, 1/2, 6mm
- Max. pressure700 PSI
- Cvmetering stem 0.019
VMGVMG Precision Metering Valve
- Port size1/4, 1/2, 6mm
- Max. pressure700 PSI
- Cvmetering stem 0.019
NVNV High Purity Needle Valve
- Port size1/4, 3/8, 1/2
- Max. pressureOn request
- CvOn request
Typical specifications
| Cv (metering) | 0.019 |
|---|---|
| Cv (regulating) | 0.30 |
| Max working pressure | 700 PSI |
| Port sizes | 1/4", 1/2", 6 mm |
| End connections | VCR, butt weld, compression, socket weld |
| Body | 316L stainless steel |
Frequently Asked Questions
Which stem should I choose for a low-flow analyser line?
The fine metering stem with Cv 0.019 gives the resolution needed for low flows; the regulating stem is better for general higher-flow setting.
Can metering valves be used as shut-off valves?
They can close a line but are not a substitute for a dedicated diaphragm isolation valve, especially on toxic gas service.
What is the maximum working pressure?
700 PSI for this family. Confirm the pressure and gas when requesting a quote.