Component line 02 / Alarm valves & switches
Wet alarm valves, waterflow indicators and the switches that report a riser
Wet alarm valves to UL 193 with their trim sets, vane-type waterflow indicators to UL 346 that actuate at 10 GPM (38 LPM), pneumatic pressure switches for dry and preaction systems, and valve supervisory switches. Supplied as components. The riser arrangement, the hydraulic calculation and the forward flow test belong to your contractor.
Standard references only. Pressure and supervisory switches are listed for fire protective signalling use; the standard and file number specific to the model appear on the certificate.
One sprinkler operating is about 10 GPM, which is why that is the flow the device has to catch.
The riser is a chain of components, and each one reports something different
A wet riser tells the panel three separate things: water is flowing, the valve is open, and the air pressure in a dry or preaction system is where it should be. Each of those is a different device, and each one has its own failure mode.
The alarm valve sits between the supply and the system and passes a metered flow to the alarm trim when a sprinkler operates. The waterflow indicator watches the pipe and closes a contact when it sees roughly one sprinkler's worth of flow. The pressure switch watches supervisory air on dry and preaction systems. The supervisory switch watches the control valve and reports the moment it leaves the fully open position.
Engineering note · the 10 GPM figure
Ten gallons per minute is 37.85 litres per minute, quoted in the trade as 38 LPM. It is the flow of a single operating sprinkler at typical residual pressures, so a device set there will not wait for a second head to open before it reports. Setting the switch higher delays the alarm and risks missing the transmission window that the installation standard allows for a waterflow alarm.
01 / Specification
Four devices, four datasheets
| Sizes | 2″, 2½″, 3″, 4″, 6″, 8″ |
|---|---|
| Metric sizes | DN50, DN65, DN80, DN100, DN150, DN200 |
| Connection | Flanged ANSI 125/150 or grooved |
| Working pressure | 175 psi ≡ 12 bar |
| Body | Cast or ductile iron, epoxy coated |
| Trim | Brass, pre-assembled or loose |
| Alarm outlet | ½″ or ¾″ NPT |
| Trim includes | Retard chamber, supply and system gauges, main drain, alarm test valve, strainer, water motor gong |
| Actuation flow | 10 GPM ≡ 38 LPM |
|---|---|
| Sizes | 2″ to 8″ (DN50 to DN200) |
| Paddle | Field trimmed to the pipe internal diameter |
| Retard | Adjustable pneumatic, up to 90 s |
| Contacts | SPDT or DPDT, 10 A at 125 / 250 V AC |
| Enclosure | NEMA 4 ≡ IP54, die-cast aluminium |
| Working pressure | 175 psi ≡ 12 bar |
| Ambient | 32 to 120 °F ≡ 0 to 49 °C |
| Function | Supervisory air supervision on dry pipe, preaction and antifreeze systems |
|---|---|
| Adjustable range | 10 to 60 psi ≡ 0.7 to 4.1 bar |
| Trip options | Low trip, high trip, or both |
| Connection | ¼″ NPT |
| Contacts | SPDT, 10 A at 125 / 250 V AC |
| Enclosure | NEMA 4 ≡ IP54 |
| Listing | Fire protective signalling use |
| Function | Reports a control valve that is not fully open |
|---|---|
| Valves served | OS&Y gate valves and butterfly valves |
| Mounting | Bracket to the valve yoke or the gearbox |
| Contacts | SPDT, 10 A at 125 / 250 V AC |
| Enclosure | NEMA 4 ≡ IP54 |
| Conduit entry | ½″ NPT |
| Listing | Fire protective signalling use |
Two settings that cause site arguments
The paddle has to be trimmed to the pipe's internal diameter before the switch is fitted, and the retard has to be set so that a genuine flow still reaches the panel inside the transmission window. Both are installation decisions, and both are the reason a correctly specified switch can still produce a wrong result.
02 / Model list
Model designations
Add what you need and the list is carried into the enquiry form. Sizes are given in both unit systems because the flange standard and the pipe schedule usually come from different documents.
| Model designation | Device | Size | Key figure | Connection | Add to model list |
|---|---|---|---|---|---|
| EMS-AV-WET-050 | Wet alarm valve | 2″ / DN50 | 175 psi / 12 bar | Flanged or grooved | |
| EMS-AV-WET-100 | Wet alarm valve | 4″ / DN100 | 175 psi / 12 bar | Flanged or grooved | |
| EMS-AV-WET-150 | Wet alarm valve | 6″ / DN150 | 175 psi / 12 bar | Flanged or grooved | |
| EMS-AV-TRIM-K | Alarm trim set | To suit valve | Retard chamber, gauges, drain, test valve, gong | Brass, NPT | |
| EMS-FS-VANE-050 | Waterflow indicator | 2″ / DN50 | 10 GPM / 38 LPM | NPT or grooved | |
| EMS-FS-VANE-100 | Waterflow indicator | 4″ / DN100 | 10 GPM / 38 LPM | NPT or grooved | |
| EMS-FS-VANE-200 | Waterflow indicator | 8″ / DN200 | 10 GPM / 38 LPM | NPT or grooved | |
| EMS-PS-PNEU-60 | Pressure switch | ¼″ NPT | 10 to 60 psi / 0.7 to 4.1 bar | Brass, NPT | |
| EMS-VS-SUP-01 | Valve supervisory switch | Universal bracket | Not fully open signal | ½″ NPT conduit | |
| EMS-AV-GONG-6 | Water motor gong | 6″ / 150 mm | Mechanical, no power supply | ½″ NPT |
Other sizes up to 8″ (DN200), higher pressure ratings and grooved or flanged variants in either standard are quoted on request.
03 / Scope
What this line ships, and what it does not
Ships from us valves and switches
- Wet alarm valve bodies in the sizes listed, with or without the trim set
- Retard chambers, gauges, drain valves, alarm test valves and water motor gongs
- Vane-type waterflow indicators with the paddle and the retard
- Pneumatic pressure switches and valve supervisory switches
- Datasheets, model list and the listing certificate with its document number
Not from us by others
- The riser arrangement and the pipework
- Hydraulic calculation and the system demand
- Paddle trimming, switch setting and retard adjustment on site
- Wiring to the fire alarm panel and the address programming
- Forward flow testing, trip testing and the acceptance test
04 / On site
What decides whether the riser reports correctly
- Alarm transmission time. The installation standards allow a defined window, in the order of 90 seconds, between sustained flow and the alarm reaching the panel. A retard set too long, or a switch set too high, eats that window before a single wire is pulled.
- Supervision of every control valve. Each control valve on the system is supervised so that a closed valve is a trouble signal rather than a surprise during a fire. That is what the supervisory switch is for, and it belongs on the valve, not on the drawing only.
- Retard chamber behaviour. The retard chamber absorbs the pressure surge that follows a small fluctuation in supply and lets only sustained flow through to the gong, which is what stops a municipal supply surge from emptying a building at two in the morning.
- Direction of flow. Flow switches and alarm valves are directional. A switch fitted against the arrow will either never trip or trip continuously, and neither of those is a component fault.
Engineering note · testing is not ours
Forward flow testing, trip testing and the acceptance test are carried out by the installing contractor and witnessed by whoever the project requires. We supply the components and the documents. If a device fails a test we will replace it and we will look at why, but we will not sign the test.
05 / Questions
Alarm valves and switches, asked and answered
Why does the waterflow indicator actuate at 10 GPM?
Because that is roughly what one sprinkler flows. The device exists to report a single operating head, not to wait for a fire large enough to open several. Ten gallons per minute is 37.85 litres per minute and is quoted as 38 LPM in metric documents.
Does the retard chamber delay the alarm past what the code allows?
Only if it is set that way. The retard exists to ignore a surge, not to ignore a flow. The adjustable retard has to be set so a genuine flow still reaches the panel inside the transmission window that the installation standard allows, and that setting is part of commissioning.
Do you supply the riser pipe and the flanges?
No. We supply the valve, the trim, the switches and the accessories. The pipework, the supports and the arrangement belong to the installing contractor, and the hydraulic calculation belongs to the designer of record.
Can one switch model be used on any pipe size?
The switch body often can, but the paddle has to be trimmed to the internal diameter of the pipe it is fitted to before installation. Order the switch for the pipe size on the drawing and confirm the pipe schedule, because the same nominal pipe size has different internal diameters in different schedules.
What documents come with a valve order?
The datasheet, the model list as supplied, the packing list and the listing certificate with its own document number, naming the holder and the issuing body. See Certification for the full document pack and the rules that apply to it.
Alarm valves & switches
Send the riser schedule and the pipe sizes
Give us the valve sizes, the pipe schedule, the flange or groove preference and the panel input type, and the quotation will come back with the switch models matched to them.
- Flow actuation
- 10 GPM ≡ 38 LPM
- Sizes
- 2″ to 8″ (DN50 to DN200)
- Enclosure
- NEMA 4 ≡ IP54
- Listing
- UL 193 valves, UL 346 flow indicators