Gauge says M20×1.5, port says 1/2" NPT — or the gauge is G1/2 and the manifold is ZG? We machine the exact adapter between any two gauge connection standards in 304/316 stainless: female × male, male × male, laser-marked with both callouts, rated to 6000 PSI. From a thread callout or a photo, MOQ 1, no CAD. Get a quote →
Four gauge standards, one instrument panel
Pressure gauges are one of the few products where four thread systems are all "standard" — which one you get depends on where the gauge and the machine were built. European gauges follow EN 837 with G1/4 and G1/2 parallel threads; the metric variant, M20×1.5 and M14×1.5, dominates gauges supplied with Asian equipment; US instruments follow ASME B40.100 with 1/8", 1/4" and 1/2" NPT tapers; and Chinese-built machinery frequently carries ZG (Rc/R) taper ports. The moment a replacement gauge, imported machine or mixed-brand skid enters the picture, two of these systems meet — and the store-bought adapter selection covers only the most popular brass pairs.
EN 837 (EUROPE)
G1/4 and G1/2 BSPP parallel threads. Seal on a bonded washer or flat gasket at the shoulder — never on the thread.
M20×1.5 / M14×1.5 (METRIC)
Metric parallel gauge stems, standard on gauges shipped with Chinese and much other Asian equipment. Shoulder-sealed like G threads.
ASME B40.100 (USA)
1/8", 1/4" and 1/2" NPT taper. Seals metal-on-metal on the taper with sealant or PTFE tape — no washer, no shoulder.
ZG / Rc / R (TAPER)
55° taper pipe threads on Chinese-market manifolds and blocks. Close to BSPT — not interchangeable with NPT's 60° form.
The combinations we machine
These ten pairings cover most gauge installations — every one is cut to order in 304 or 316 stainless, so any other pairing is exactly as available:
| Gauge end (female) | Port end (male) | Typical use |
|---|---|---|
| M20×1.5 | 1/4" or 1/2" NPT | Asian/EU gauge onto US manifold — our most-ordered conversion |
| M20×1.5 | ZG1/4 · ZG3/8 · ZG1/2 | Standard gauge onto Chinese-built machine port |
| M14×1.5 | ZG1/4 · ZG3/8 · ZG1/2 · M20×1.5 | Small-dial gauges, compact hydraulic blocks |
| G1/2 | M20×1.5 · M14×1.5 · NPT | EN 837 gauge onto metric or US port |
| 1/4" NPT | M20×1.5 · G1/2 | US gauge or transmitter onto imported equipment |
Male × male nipple forms, reducing bushings and extended-reach bodies are machined from the same bar. If the pairing you need reads strangely — that's normal; strange pairings are our order book.
How each end seals — and why it matters
A gauge adapter joins threads that seal by different rules, and mixing the rules up is how installations weep. Parallel ends (M20, M14, G) never seal on the thread: we machine the shoulder flat and square for a bonded (Dowty) washer or gasket, the way EN 837 intends. Taper ends (NPT, ZG/R) seal metal-on-metal as they wedge tight, with sealant or tape per your site practice — and we cut them to gauge so they make up hand-tight plus the standard turns, not two threads early. Where the reading pulses (pumps, presses), we can drill the bore as a restrictor/snubber orifice to damp the needle — say so in the RFQ and it costs nothing extra to machine.
Specifications
| Attribute | Standard build | On request |
|---|---|---|
| Threads | M20×1.5 · M14×1.5 · G1/4–G1/2 · ZG1/4–ZG1/2 · 1/8"–1/2" NPT | BSPT, UNF, left-hand, 13/16-28 UN, any pairing |
| Configuration | Female × male | Male × male · female × female · extended reach |
| Material | 304 stainless steel | 316 stainless · 303 free-machining · brass C360 · 6061 / 7075 aluminum (dry-gas panels) · 4140 steel for high-pressure test rigs |
| Pressure | Up to 6000 PSI (size-dependent) | Verified rating stated on drawing |
| Temperature | −196 °C to 450 °C | Per material and seal choice |
| Bore | Full instrument bore | Restrictor / snubber orifice Ø0.3–1.0 mm |
| Marking | Laser-etched thread callouts + material | Your part number or logo |
Gauge thread you can't identify? Send a photo of the stem next to a ruler and tell us what the gauge came off. Identifying the thread — including the odd ones like 13/16-28 UN diaphragm-seal connections — is part of the free drawing we make before you order. See our 13/16-28 UN → M20×1.5 adapter for one we already cut as a standard.
Related adapters we machine
Instrument sensors and transmitters have their own port zoo — that's covered on our sensor thread adapters page. This page is the gauge side: dial gauges, pressure switches and their panel and manifold ports.
Where the Gauge Adapter Catalogue Stops
The common gauge conversions are stocked as standard parts. These are the ones we get asked for instead.
| What you need | In the catalogue? | How we machine it |
|---|---|---|
| A standard M20×1.5 to 1/4″ NPT gauge adapter | Stocked | Buy it off the shelf — it is the most common conversion there is. |
| Male × male, or female × female | Thin | Stock gauge adapters are female × male. The other genders are made to order. |
| An extended reach so the gauge clears the manifold | No | Body length to your clearance rather than a catalogue length. |
| A left-hand thread on either end | No | Listed on this page as on request for exactly this reason — nobody stocks it. |
| 13/16-28 UN or another instrument thread | No | Cut to its own pitch and flank angle, paired with whatever your port is. |
| 316 stainless, 303, brass C360, aluminium or 4140 | Partly | Standard build is 304. The rest are on request and turned from bar. |
| A verified pressure rating stated on the drawing | No | Rating is size-dependent; we state it rather than leaving you to assume it. |
Thread pairings and materials above are the ones already listed in the specification table on this page.
Frequently asked
What thread is on my pressure gauge?
EN 837 gauges: G1/4 or G1/2. Asian-supplied gauges: usually M20×1.5 (100 mm dials) or M14×1.5 (63 mm dials). US gauges: 1/8", 1/4" or 1/2" NPT. Chinese machine ports: often ZG taper. Measure OD and pitch, or send a photo with a ruler — we identify it as part of the free drawing.
Can I put an M20×1.5 gauge on a 1/2" NPT port?
Yes — female M20×1.5 for the stem, male 1/2" (or 1/4") NPT into the port. It's the most common conversion we cut, and each one is laser-marked with both callouts.
What pressure are they rated for?
Machined from solid 304/316 bar: typically to 6000 PSI depending on size — above the range of most gauges they carry. Verified rating goes on your drawing.
Do you make combinations no catalog stocks?
Constantly — odd pairings, left-hand, extended reach, snubber bores. One piece up, from a callout or sample, no CAD needed.
Tell us both ends and the duty. "M20×1.5 female to 1/4 NPT male, 316, glycerine gauge on a 3000 PSI test pump" is a complete RFQ. Free drawing, quote in 12 hours. Get a quote →