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Senior Member

Posts: 21

Location: USA


Monday, December 24th 2001, 1:05pm

Water drain before backflow preventor

Should a water drain be installed before the backflow preventer in
order to make winterization easier; drain between valves and water meter. Also, where should ports be incorporated in the piping system in order to blow out the system for winterization?


Posts: 60

Location: USA


Thursday, January 3rd 2002, 9:55am

<b>An automatic drain valve <u>should not</u> be installed before the backflow prevention device. However, a manual drain valve can be installed in the mainline piping!</b>

<b><u>Manual Drain Valve:</u></b> The manual drain valve should be installed on the sprinkler system mainline at the lowest point of the system. Additional manual drain valves must be installed if there are multiple low points along the run of pipe where water collection might occur. A ball valve, gate valve, "Stop and Waste" valve, or a simple threaded pipe with a cap may be used to provide drainage. Piping should be sloped properly to allow water to drain out. If the valve is located outdoors, it should be installed over a "dry-well" (underground pit filled with gravel to drain water away from the piping) to allow the amount of water that is drained to percolate into the soil. If the valve is installed indoors, make sure the volume of water can be collected or drained without the risk of overflow or flooding.

<b><u>Automatic Drain Valve:</u></b> Caution! Do not install automatic drain valves on the sprinkler system mainline! The automatic drain valve, model 16A-FDV, is a spring loaded device which is installed on the sprinkler pipes or heads. It is a convenient and efficient product for removing water from the lateral pipe network running from the sprinkler system control valves to the heads. Automatic drains should be installed after or downstream of the sprinkler control valves. They are not designed or engineered for use on mainlines. The drain valve will open every time the system is shut off. This will drain all the water out of the pipe providing the valve is installed at the proper location, which is the low point on the line. When the system is pressurized, the water shuts the valve off by pressing against the sealing mechanism, allowing water to flow through the pipe and on to the sprinklers in proper fashion.

Install automatic drain valves at the low points in the sprinkler lines. Generally speaking, one or two drains per line are adequate to do the job. The drain valves have either 1/2"or 3/4" male pipe threads. Use two or three wraps of teflon tape around the threads to ensure a proper seal. Simply screw the drain valve into a threaded fitting positioned downward. If you have a soil condition which drains poorly, we suggest digging a small hole directly beneath the drain and filling it with gravel to assist drainage.

Automatic drain valves remove water from the system every time it is shut off. No manual intervention should be required. Check for excessive puddling on the soil surface should one of the drains become stuck open during sprinkler operation.

For more information on how to use drain valves or to review this information WITH PICTURES, click on the link below:

To learn how to correctly, and safely use compressed air to blow out the sprinkler system lines in regions that freeze, please read the Reply below, and then click on the following link:
<img src=icon_smile.gif border=0 align=middle>

Edited by - SprinklerWarehouse Irrigator on Jan 03 2002 3:58:12 PM

Edited by - SprinklerWarehouse Irrigator on Jan 03 2002 4:10:37 PM

Posts: 60

Location: USA


Thursday, January 3rd 2002, 10:08am

<b><u>If you Are Not Going To Use Drain Valves:</u></b>

<b>For Areas That Do Not Experience Significant Freeze:</b>
Typically, in order to drain the water between the water meter and the valves, a ball valve should be installed just pass the water meter or if you are not supplying the sprinkler system from the water meter, the ball valve should be installed just down stream from the point of connection . This will allow you to shut off the water supply to the sprinkler system without shutting off the water supply to the house. Once you shut off the water supply, you can relieve the pressure in the lines by:
1. Opening all the test cocks on the side of the Backflow prevention device to allow the main line piping to be open to atomspheric pressure. Leave them open until you repressure the system after the freeze is over.
2. Or you can manually open the zone valves to relieve the pressure by using the manual on button on your controller.

<b>For Areas that Experience Significant Freeze:</b>
Compressed air is used to force water through all of the irrigation system components including the mainline pipe, sprinkler control valves, lateral pipes, and out through the sprinkler heads. To obtain proper air volume, you will need to rent or buy a compressor capable of providing 10 to 25 cubic feet per minute (CFM) of air volume. Air pressure must not exceed 50 pounds per square inch (psi) during the blow out procedure. A pressure regulating valve must be used to avoid overpressurization of the system. Air volume should be high and air pressure low. This combination of high volume and low pressure will minimize the damage that can occur during the winterization process. It is very important to select the right air compressor for the job. Some small shop compressors (2 hp) may not be adequate to complete the winterization procedure properly.

There should be a separate provision on the sprinkler system mainline for hooking up the air hose. This could be a quick <u>connect fitting</u>, a manual gate valve, a plugged "tee", or simply a capped pipe in the line. This adapter should be located as close to the water source as possible. Check with your air compressor manufacturer for the correct procedure and equipment to hook up to the sprinkler system.

To learn how to correctly, and safely use compressed air to blow out the sprinkler system lines, click on the following link:
<img src=icon_smile.gif border=0 align=middle>

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