You fit a pressure gauge on a pump set or a PRV station, isolated with a mini ball valve. It works, but the needle flickers with every pump start. You can't crack it open gently to take a reading, and the gauge has a short, hard life.
Gauge lines, sample points, bleed-offs and instrument connections need finer control than any quarter-turn can give. That's the needle valve's job.
Zetco's new range has three: two WaterMarked bronze valves and a 316 stainless one rated to 41,300 kPa.
What a Needle Valve Does Differently
A needle valve has a long, fine-taper needle that seats into a small orifice. Several turns of the handle move it a tiny distance, so you get precise, repeatable control over very small flows.
On the job that means:
- Gauge isolation and damping: crack it just open and the gauge reads without slamming on every pressure spike
- Sample points: draw a controlled trickle instead of a blast
- Bleeds and vents: let air or pressure off slowly
- Instrument tappings: fine isolation on small-bore lines to switches and transmitters
What it doesn't do is flow. The orifice is small, so it's not an isolation valve for a branch line. For small-bore on/off, use a mini ball valve. See our special-duty ball valve guide.
Bronze Inline: Series 1725
The Zetco 1725 bronze needle valve is the straight-through pattern.
- 6, 10, 15 and 20mm, female BSP
- Water 2500 kPa (-10°C to 99°C), steam 1050 kPa @ 186°C
- Listed by Zetco as WaterMarked to AS 1628 (WM-020284)
It's the default for gauge lines and sample points on potable water, hot water plant and low-pressure steam. Being WaterMarked matters here. A gauge tapping or sample point on a potable system is part of that system, so the valve needs to comply.
Bronze 90° Angle: Series 1724
The Zetco 1724 angle needle valve turns the line through 90° inside the valve body.
- 6, 10 and 15mm, female BSP
- Water 3200 kPa (-10°C to 99°C), steam 1400 kPa @ 198°C
- Also listed as WaterMarked to AS 1628
The angle saves you an elbow, which matters on gauge tappings coming straight off the side of a header or pump casing. It turns the gauge to face the front, with one less joint to leak and a shorter overhang.
It's also rated higher than the inline version on both water and steam.
316 Stainless High Pressure: Series 2803
The Zetco 2803 stainless needle valve is the industrial option.
- 3–25mm, female BSP
- Rated 41,300 kPa (6000 PSI), 0°C to 200°C
- 316 body, PTFE stem packing
It's for hydraulic lines, high-pressure test rigs, instrumentation and process gauges. Zetco lists it as not WaterMarked and intended for instrumentation, hydraulic and process service, not potable water.
If you're hydrostatically testing a system and need a controlled bleed or gauge isolation that won't be the weak link, this is the one.
Install Tips
- Don't overtighten. The fine needle and seat are easy to damage. Close until it seats, then stop.
- Mind the flow direction. Check the body marking and fit it the right way round.
- Set gauges and leave them. For damping, crack the valve just enough that the gauge responds without bouncing.
- Use PTFE tape or sealant rated for the service. On steam, use a sealant rated for the temperature.
Quick Picker
- Gauge or sample point on potable or hot water: 1725 inline
- Gauge tapping off a header or casing, where you want to lose an elbow: 1724 angle
- Hydraulic, test rig or high-pressure process: 2803 stainless
The Short Version
Use a needle valve wherever you need fine control on a small flow: gauges, samples, bleeds and instruments. Go bronze WaterMarked for potable water and steam, and 316 for high-pressure and process work.
Browse them in the Zetco and valves collections. If you're choosing a gauge to go with one, see our digital manometer guide. For regulating bigger flows, see globe valves.
Frequently Asked Questions
What is a needle valve used for?
Fine control of small flows: gauge isolation and damping, sample points, bleeds, vents and instrument connections. It's not intended as a full-flow isolation valve.
Do I need a WaterMarked needle valve on a gauge line?
If the gauge or sample point is on a potable water system covered by AS/NZS 3500, the valve is part of that system. Zetco lists the bronze 1725 and 1724 as WaterMarked to AS 1628.
Why use an angle needle valve?
The 90° body replaces an elbow, which shortens the overhang and removes a joint on gauge tappings off headers and pump casings.
How much pressure can the 316 needle valve handle?
Zetco rates the 2803 to 41,300 kPa (6000 PSI) from 0°C to 200°C. It's for hydraulic, instrumentation and process work, not potable water.