Tyco Star A-1 - User Manual

The Star 4 inch (DN100), Model A-1 Dry Pipe Valve, also known by part number #1097, is a differential valve designed for automatic control of water flow into dry pipe fire protection sprinkler systems upon the operation of one or more automatic sprinklers. It also facilitates the actuation of fire alarms when the system operates.

Function Description:

Dry pipe sprinkler systems are typically employed in unheated environments such as warehouses, parking garages, store windows, attics, and loading docks, where water-filled pipes are not feasible due to freezing temperatures. When in service, the system piping is pressurized with air (or nitrogen). A loss of air pressure, typically due to an activated automatic sprinkler in response to heat from a fire, causes the Model A-1 Dry Pipe Valve to open, allowing water to flow into the sprinkler system piping.

The valve's differential design means that the minimum air pressure required in the piping is approximately 1/5 of the static water supply pressure, with an added safety factor to prevent false operations caused by water supply pressure fluctuations. This differential nature is based on the area difference between the air seat and the water seat, such that 1 psi (0.07 bar) of system air pressure can hold approximately 5 psi (0.34 bar) of water supply pressure.

Priming water within the valve body helps maintain a tight air seal at the air seat. An intermediate chamber, located between the air and water seats, is normally open to the atmosphere through the alarm port and piping to the Automatic Drain Valve (5 - Fig. 4). This open intermediate chamber is crucial for the valve to remain set, as it ensures the full system air pressure acts on the Clapper Assembly. If pressure were trapped in this chamber, it would reduce the effective holding force on the Clapper Assembly. When sprinklers operate, air pressure in the system piping is relieved. Once the air pressure drops sufficiently, the water supply pressure overcomes the differential holding force, causing the Clapper Assembly to swing open and allow water flow. Under full flow conditions, the Clapper Assembly remains open, and the intermediate chamber is pressurized, with water flowing through the alarm port to actuate system waterflow alarms. This flow also closes the normally open Automatic Drain Valve.

Optionally, the Model A-1 Dry Pipe Valve can be equipped with a Model S430 Dry Pipe Valve Accelerator to reduce the time for the valve to open after sprinkler operation. This accelerator may be required for systems with capacities exceeding 500 gallons (1890 litres) as per NFPA 13 requirements.

Important Technical Specifications:

Approvals: UL and ULC Listed, FM and LPC Approved.
Working Water Pressure: 20 to 175 psi (1.4 to 12.1 bar).
Friction Loss: Refer to Figure 3 for detailed flow rate vs. pressure drop.
System Air Pressure Requirements: Refer to Table A for recommended minimum and maximum air pressures based on water supply pressure.
Physical Characteristics: Body components are constructed of cast iron. The seat ring is copper, and the clapper is ductile iron with a Buna-N facing.
Installation: Must be installed vertically as shown in Figure 6, in a readily visible and accessible location, maintained at a minimum temperature of 40°F/4°C. Heat tracing of the valve or its associated trim is not permitted.
Trim: The valve must be trimmed in accordance with Figures 4 and 5. All nipples, fittings, and devices must be clean and free of scale and burrs. Pipe thread sealant should be used sparingly. Check valves, strainers, and globe valves must be installed with flow arrows in the proper direction.
Drainage: Provision must be made for disposal of drain water to prevent accidental damage or danger.
Pressure Relief Valve: Must be set to relieve at approximately 5 psi (0.34 bar) higher than the required system air pressure.
Air Maintenance Device: Installation of an Air Maintenance Device, which provides a restricted air inlet for automatic air supply, is recommended.
Inspector's Test Connection: Required by NFPA 13 on the system piping at the most remote location from the valve.
Hydrostatic Tests: Before performing hydrostatic tests, the Clapper Assembly must be manually latched open (Ref. Figure 2-C), the Automatic Drain Valve temporarily replaced with a 1/2 inch NPT pipe plug, and Handhole Cover Bolts tightened using a cross-draw sequence. If an accelerator is used, its control valve must be closed.

Usage Features:

Automatic Operation: Automatically controls water flow upon sprinkler activation.
Alarm Actuation: Provides for fire alarm actuation upon system operation.
Differential Design: Ensures reliable operation with a calculated air pressure ratio to water supply pressure.
Optional Accelerator: Can be fitted with a Model S430 Dry Pipe Valve Accelerator for faster opening times, potentially required for larger systems.

Maintenance Features:

Setting Procedure: Detailed 14-step procedure for initial setup, after operational tests, or after system operation due to fire. Includes closing valves, draining, verifying Automatic Drain Valve operation, replacing sprinklers, cleaning internal parts, reseating the Clapper Assembly, replacing the Handhole Cover, priming the valve, pressurizing the system, and checking for leaks.
Annual Operation Test: Verification of proper valve operation at least once a year. Involves closing the main control valve, opening the main drain, opening the inspector's test connection, verifying valve operation and alarm activation, closing the main control valve, and resetting the valve.
Quarterly Waterflow Alarm Test: Testing of system waterflow alarms by opening the Alarm Test Valve.
Weekly Inspections:
- Water Pressure Inspection: Check the Water Pressure Gauge weekly to ensure normal system water pressure.
- Air Pressure Inspection: Check the Air Pressure Gauge weekly to ensure normal system air pressure.
- Automatic Drain Valve Inspection: Depress the plunger weekly to check for water/air discharge, which indicates leaks in the air and/or water seats. If leakage occurs, the valve must be taken out of service for inspection of the Clapper Facing, Alarm Test Valve, and Air/Water Seat Rings.
Quarterly Priming Water Inspection: Partially open the Priming Test Valve to check the priming level. Replenish if no water discharges.
Component Inspection: Regular inspection of Clapper Facing for compression set or damage, Alarm Test Valve for complete closure, and Air/Water Seat Rings for nicks. Worn or damaged parts must be replaced. Air and Water Seat Rings are not field replaceable, requiring valve replacement if damaged.
Notification: Proper authorities and personnel monitoring alarms must be notified before performing operational tests or maintenance that involves closing the main control valve.