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 · brass · 6061 aluminum (dry-gas panels) |
| 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.
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 24–48 hours. Get a quote →