Water spray systems play a vital function in aggregate operations. Learn how to keep their productivity high as the temperatures fall.

by Mark Kestner, Ph.D.

Water spray systems have long been used to control dust produced by quarry operations. They protect workers from exposure to silica containing dusts and prevent visible emissions that upset neighbors. But what happens when the temperatures drop below freezing and winter weather challenges operators that have to keep spray systems running?

Once the leaves begin to fall and the north winds begin to blow, it’s time to winterize your spray system. An early frost can catch the plant unaware and freeze up hose, pipe, and nozzles. If the pump freezes up and bursts, that’s real trouble. When this happens, the plant can’t operate until the system is thawed or repaired and that means lost production. If operators have to spend a couple of hours a day thawing out nozzles, the dollars can really add up. The busy quarry operation would be wise to plan ahead and install a system that will minimize downtime during the winter.

Here are some guidelines for operating spray systems in cold weather:

1. Install a thermometer to alert operators to freezing temperatures so they can take action before nozzles freeze up.

2. Inspect spray nozzles daily to make sure that they are not plugged or frozen.

3. Inspect the pump daily. Verify that the pump is heated and that the inlet water line is not frozen.

4. Minimize the number of spray nozzles in service. Use only essential spray nozzles.

5. Consolidate spray nozzles. Using a single nozzle instead of two or three nozzles at the same spray point reduces the number of nozzles to maintain and allows the use of larger orifice nozzles that are less likely to freeze.

6. Make sure that nozzles are properly targeted and do not spray steelwork or conveyor belting.

7. Make sure water lines run straight and true and that drain valves are located at all low points where water can collect.

8. Drain water lines and nozzles immediately after they are taken out of service and leave drain valves open overnight. Do not allow water to sit in hose lines and spray manifolds.

Many quarries have taken winter operation a step further and installed compressed air and anti-freeze purge systems to protect water lines and nozzles from freezing. These add a serious measure of protection that any state-of-the-art quarry can ill afford to be without.

Advanced wet suppression system designs consolidate all moving parts onto a skid-mounted pump module where they can be protected. No solenoid valves are located outside where they can freeze and burst. Most importantly, the pump module must be housed in a heated enclosure. Thermostatically controlled convection or forced-air heaters can also be mounted directly on the pump skid to keep critical components from freezing. For portable plants, the pump module, surge tank, or other accessory equipment can be housed in a heated trailer.

Hose or pipe is used to supply water to nozzles. Hose has the advantage of being a better insulator and won’t freeze as fast, but it cannot be thawed with a torch like pipe.