Same part, five names. Five connections, eight gases, one cheat sheet — for the technicians who already know what an outlet does and just want the terminology to stop fighting back.
2 assemblies5 connection styles8 US gas colors1 page
The wall fixture you've installed a thousand times.
An outlet is the wall-mounted fixture where clinical staff plug in a flowmeter, ventilator, suction regulator, or anesthesia machine. Strip away the marketing names and you have a behind-wall assembly brazed to the gas line, and a removable face that accepts the adapter. Two parts. That's it.
An outlet point in a piped medical gas distribution system at which the user makes connections and disconnections.
— NFPA 99, 2024 · §3.3.182 (Station Outlet)
NFPA calls it a station outlet. Older specs call it a gas terminal. Vacuum codes call it an inlet. In the field, your team calls it whatever the last person they trained called it. Let's untangle the rest.
Anatomy
It's just two pieces.
Behind every faceplate there are two main assemblies. The naming trouble starts the moment you try to talk about them. Click either piece to see the dozen-or-so names you'll hear in the wild.
Back body / rough-inFront body / faceplate
Connection styles
Five connections, one job.
If outlets followed an NEMA-style standard, this section wouldn't exist. They don't, so here it is — including the retrofit-kit picture, which is what facilities actually care about when they want to standardize without re-piping the building.
Pin-Index
Ohmeda · Diamond · Diamond II · DiamondCare · Medaes
Two stainless pins on the front body slot into gas-specific bores on the rough-in. The adapter twists in a quarter-turn to lock.
Who makes it
BeaconMedaes (Diamond, Diamond II, DiamondCare). Originally Ohmeda. The most common new-construction connection in North American hospitals.
Cross-compatibility
Allied's Connect2 outlet accepts Ohmeda adapters with a twist release. Amico, Tri-Tech, and Ohio Medical all sell front-body retrofit kits that mount on competing rough-ins.
Latchkey
Chemetron · NCG · Allied Chemetron
Two spring-loaded latches grip the adapter at the sides. Push the front of the adapter in, the latches snap home; press both releases simultaneously to remove.
Who makes it
Allied Healthcare Products (the current owner of the Chemetron line). Extremely common in older US hospitals and renovations.
Cross-compatibility
Allied Connect2 accepts Chemetron adapters with a push-button release. Tri-Tech and Amico both publish Chemetron-to-Pin-Index conversion kits — the most common retrofit pattern in the field.
Geometric
Puritan Bennett · PB
Each gas has a uniquely shaped socket — a triangle, a slot, a notched rectangle. The adapter physically can't seat in the wrong outlet.
Who makes it
Originally Puritan Bennett (now part of Medtronic). The pure Geometric style is largely a legacy install — you'll find it in older hospitals that haven't standardized.
Cross-compatibility
Ohio Medical still produces Puritan-Bennett-compatible front bodies. Most facilities choose to retrofit these to Pin-Index or DISS rather than continue the format.
DISS
Diameter Index Safety System · CGA V-1
A threaded fitting with gas-specific thread diameters and nipple geometry. Hand-tight, then a wrench-snug. Manufacturer-agnostic by design.
Who makes it
Everyone. DISS is the CGA V-1 standard, not a proprietary connection. You'll see it on anesthesia machines, ventilator high-pressure inlets, OR ceiling columns, and high-flow specialty outlets.
Cross-compatibility
Universal. Every major manufacturer ships a DISS front body that mounts on their own rough-in, and most retrofit kits offer a DISS option for any legacy rough-in.
Oxequip
Medstar · Med*Star · '07 Series
A round quick-connect adapter with self-sealing poppet — once common in Canadian and select US installations. Now niche.
Who makes it
Allied Medical (which now distributes the Oxequip Med*Star line). UL-listed, CSA-compliant; still supported but rarely specified in new US construction.
Cross-compatibility
Limited. Allied still sells Medstar replacement front bodies for installed rough-ins. Most facilities retrofitting Medstar today are going to Pin-Index or DISS.
Color codes
Know the color, know the gas.
The eight pipeline colors you'll see on every faceplate. They're rigid for a reason — color is the first line of defense against a wrong-gas connection. If you ever specify or buy parts internationally, scroll past the US grid; the differences matter.
Used outside the US (UK, EU, Canada hospital piping, parts of LATAM)
Differs
Oxygen
O₂
ISO uses white, not US green.
Differs
Medical Air
MED AIR
ISO: black-and-white check, not US yellow.
Nitrous Oxide
N₂O
Blue — same as US.
Differs
Medical Vacuum
VAC
ISO: yellow, not US white.
Nitrogen
NIT
Black — same as US.
Carbon Dioxide
CO₂
Gray — same as US.
WAGD
WAGD
Purple/violet — same as US.
Differs
Instrument Air
IA
Often shown as black-and-white check with red overlay; not specified in ISO 32 for all jurisdictions.
The biggest gotcha: oxygen is green in the US and white in most of the rest of the world. If you ever buy adapters, hose, or testing gear from a non-US supplier, double-check the color spec on the packaging before it confuses a tech in the field.
Repair or replace
When to swap, when to shut down.
Two-piece design isn't just academic — it determines whether you can fix the outlet during business hours or whether you need to plan a downtime. Quick rule: front-body issues are usually swaps; back-body issues are usually shutdowns.
Usually a swap
Front-body symptoms
Sticky or stuck adapter release
Worn or damaged indexing pins / latches
Cracked, faded, or mis-labeled faceplate
Slow secondary-check leak (faint hiss with no adapter inserted)
Wrong gas color showing up (legacy mislabel)
You can swap a front body with the room in service. The primary check valve in the rough-in keeps the line sealed the moment the faceplate comes off. Document the part swap, repressurize, particulate-test, and you're done.
Plan a shutdown
Back-body symptoms
Brazed-joint leak (soap test bubbles at the wall)
Damaged primary check (line won't hold pressure after faceplate removed)
Cross-threaded or compromised inlet pipe
Wrong-gas indexing on the rough-in (rare but catastrophic)
Drywall water damage that crushed the box
Replacing a rough-in means isolating the zone valve, depressurizing, opening the wall, re-brazing, and re-certifying the outlet. Pull a permit, coordinate with clinical, plan for the room to come offline, and retest per NFPA 99 §5.1.12 before returning to service.
Retrofit kits
Upgrade the outlet, keep the wall.
The single most underrated tool in the outlet world. A retrofit kit lets you mount a modern front body onto an old rough-in — different connection style, same copper. The wall stays closed, the room stays in service, and your facility moves one step closer to standardization.
Why facilities use them
Standardize the facility on one connection style (usually Pin-Index or DISS) without re-piping.
No drywall work, no permit, no brazer, no zone-valve shutdown.
Modern parts availability — older Chemetron and Oxequip rebuild kits are getting scarcer every year.
Easier adapter release for clinical staff, fewer dropped flowmeters.
Common retrofit patterns
Chemetron→Pin-Index
Puritan Bennett→DISS or Pin-Index
Oxequip / Medstar→Pin-Index
Legacy Ohmeda→DiamondCare
Vendors to know: Allied's Connect2 line (accepts Ohmeda and Chemetron adapters in the same outlet), Tri-Tech conversion kits (DISS into legacy rough-ins), Amico universal front bodies, and Ohio Medical's multi-format catalog. BeaconMedaes also publishes manufacturer-direct retrofit kits for their DiamondCare line onto older Diamond II rough-ins.
Verify before you button up. Indexing matters. A retrofit kit that mixes O₂ indexing pins with a vacuum rough-in is a never-event waiting to happen. Always confirm the gas-specific keying on both halves and re-run NFPA 99 §5.1.12 verification (cross-connection, particulate, purge) before the outlet goes back into clinical use.
Take the full course
Want the whole curriculum?
This is the cheat-sheet version. Lantern's Master Med Gas Technician course (Outlets 101–104) covers all of this plus model-specific repair tutorials, leak-test procedures, retesting documentation, and the safety rules that keep your team out of trouble in occupied rooms.
