Reliable B1 Accelerator with Accelo-Check for Dry Pipe Valves

The Reliable B1 accelerator with integral Accelo-Check (an anti-flooding device) speeds up the operation of dry pipe valves and of the deluge valves used on certain preaction systems. Faster valve operation can allow more sprinklers to be controlled by one dry pipe valve and a larger dry system volume. It is normally closed, with 1/2 in (15 mm) NPT inlet and outlet ports, and it is cULus Listed and FM Approved; LPCB is also listed in Bulletin 323 (June 2025).

How the accelerator works

On setup, system air passes the filter into the middle chamber, lifts the diaphragm assembly off the push rod and fills the top chamber to system pressure. The diaphragm then closes the passage to all but very small air movements, so slow changes from temperature or minor leaks equalise without tripping. When a significant pressure decay occurs, as when a sprinkler opens, the retained top-chamber pressure forces the poppet open once the difference between the top and middle chambers reaches about 3 to 4 psi (21 to 28 kPa). System air then flows out of the outlet port to the intermediate chamber of the dry pipe valve and trips it, while the Accelo-Check closes to keep water and debris out of the internal restriction.

Key features from the bulletin

• Hastens dry pipe valve operation and can increase the sprinklers per riser.
• Equalises quickly while the dry system is filled to pressure and self-adjusts to small air pressure fluctuations.
• Compact, light-weight construction.
• Accelo-Check protects the restriction passage from water and debris.
• Tested and approved for use with Reliable dry pipe and preaction systems.

Technical specifications and compatibility

Table A of Bulletin 323 lists the kit part numbers by valve.

System requirements and installation

NFPA 13 permits approved quick-opening devices on dry pipe and double interlock preaction systems. On systems between 500 gallons (1900 L) and 750 gallons (2850 L) the 60-second water delivery requirement may be waived; above 750 gallons the device lets the valve open early so water can travel the network. Systems under 500 gallons do not generally use accelerators. On Model D and FX valves the outlet connects directly to the intermediate chamber; on DDX-based dry systems the outlet is vented to atmosphere and purges the pneumatic actuator. A steady regulated air supply, preferably a tank-mounted compressor with a listed pressure maintenance device, is strongly recommended.

Resetting and maintenance

The reset procedure must be followed every time the system operates or is tested: isolate the accelerator, reset the main valve, remove the drain plugs, dry the chambers if water is present, purge, reinstall the Accelo-Check and re-pressurise so the top chamber equals system pressure. The bulletin recommends a semi-annual trip test by loosening the 1/4 in body drain plug and includes a troubleshooting table for leakage, flooding and failure to trip.

Typical applications

Large dry pipe systems in unheated warehouses, cold stores, car parks and plant areas benefit from faster water delivery. Bulletin 323 cautions that accelerator operation and water delivery at the inspector test connection do not happen at the same time, because air must be expelled first.

Selection and installation notes

A fire protection valve is only one part of a sprinkler system, which must be designed, installed and commissioned by qualified people to the standard and the authority rules that apply to the project. Confirm the size, the pressure rating and the trim configuration against the design, install the valve in the position and orientation in the manual, fit the drain and alarm connections as drawn, test the alarm and the flow before handover and keep the inspection and test records. Check the listing and approvals needed for the project with the authority before purchase.

Information needed for a quotation

Send the full model code, the quantity, the delivery location in Oman or the GCC, the intended use and any accessories needed, so that the complete package can be quoted together.

Documents and supply information

The manufacturer data sheet is attached to this page and should be read together with the project specification and the site risk assessment before a purchase is confirmed. Ratings, standards and dimensions are quoted as printed on that sheet. Lead time, stock position and certificates available with the shipment are confirmed in the quotation, and we supply to Oman and the wider GCC region for industrial, utility and building services projects.

Related items and documents

Fit with the Reliable FX dry pipe valve (Bulletin 360). The bulletin is hosted on this page. Seven Star LLC is an independent supplier in Muscat; see the Fire Fighting range or tell us the host valve and size for a quotation.

Frequently asked questions

What does the Accelo-Check do?

It is an anti-flooding device that closes when the accelerator operates, keeping water and debris out of the internal restriction area.

Which valves can the B1 be fitted to?

Reliable FX, DDX-LP, DDX Type F and Type PL, plus legacy Model D and EX valves, using the kit numbers in Table A.

At what pressure difference does it open?

At approximately 3 to 4 psi (21 to 28 kPa) between its top and middle chambers.

Is it approved for any system volume?

It is UL Listed and FM approved for system volumes up to 1500 gallons (5678 L).

Can it be used with non-Reliable valves?

The bulletin says it may hasten other valves but has only been tested and approved with Reliable valves.