Diaphragm Pumps

Sodium hypochlorite eats plunger pumps for breakfast, which is why every serious soft wash rig runs a diaphragm pump instead. Sun Brite Supply carries diaphragm pumps from Everflo, FloJet, AR, and Comet, from a $51 spot sprayer pump to gear driven gas units that push 9 GPM. Building or fixing a soft wash system? Call 301-519-9274 and we will size the pump to your tank, hose, and targets.

Why Soft Wash Systems Use Diaphragm Pumps

A diaphragm pump moves liquid by flexing a chemical resistant membrane instead of sliding metal plungers through seals. The bleach never touches bearings or pistons, and the wetted parts are polypropylene, Santoprene, and Viton, materials that shrug off sodium hypochlorite, surfactants, and most roof wash mixes. That design also lets these pumps run dry briefly and self prime, two things that kill a plunger pump fast. The trade is pressure. Diaphragm pumps live in the 60 to 300 PSI range, which is exactly what soft washing wants, since the chemical does the cleaning and the water just delivers it.

12 Volt Electric or Gear Driven Gas

A 12 volt pump wired to a deep cycle battery is the standard starter setup. It is quiet, cheap to buy, and simple, with a built in demand switch that starts the pump when you pull the trigger. Real world numbers run 1 to 7 GPM, enough to treat a two story house from the ground with the right nozzle. The weak points are the motor and the pressure switch, and when a 12 volt unit dies it usually costs more to fix than replace. Gear driven diaphragm pumps on gas engines are the production step up. An AR252 moves 6.5 GPM at 362 PSI and a Comet P36 moves 9.3 GPM, enough reach for steep roofs and multi story work, and both rebuild with off the shelf diaphragm and valve kits instead of hitting the trash can.

Match the Pump to the Work

Spot treating and small jobs run fine on a 1 GPM pump. House washing wants 5 GPM or better so you are not waiting on rinse. Roof work rewards 7 GPM and up because SH mix needs to land wet and keep running. Crews with two guns on one system should look straight at the gear driven units, since splitting a small pump between two operators leaves both of them starving.

Diaphragm Pump Lineup

The FloJet Pentaflex and the Everflo 1.0 GPM were both on the shelf when this page was written. Everything else moves in and out, so call to confirm before you drive.

From the Field

The pumps that come back to our counter dead almost all died the same way: parked wet. SH left sitting in the head dries into salt crystals that chew the diaphragm and jam the check valves, so flush the system with fresh water at the end of every day, every time. Three more habits that stretch pump life. Feed the pump from the top of the tank with a wide suction line and a mesh strainer, because a starved or gritty inlet flexes the diaphragm harder than any pressure setting. Keep the battery strong, since low voltage makes 12 volt motors run hot and burns pressure switches. And buy the rebuild kit with the gear driven pump, not after it fails on a roof job in July.

Related Collections

• Soft wash equipment and 12 volt pumps
• Roof cleaning chemicals and house washing chemicals
• Chemical hoses and chemical injectors
• Water tanks and chemical handling
• Sprayers and pump accessories
• Pressure washer pumps for the high pressure side of the rig

Building a full soft wash trailer? Come talk it through at our Gaithersburg store before you buy the first part.

Frequently Asked Questions

Can a diaphragm pump handle bleach?

Yes, that is the main reason soft washers use them. The wetted path is polypropylene and chemical resistant elastomers like Santoprene and Viton, so 12.5 percent sodium hypochlorite and surfactants pass through without attacking metal internals. Flush with fresh water after each use and the materials last for seasons.

What size diaphragm pump do I need for house washing?

Around 5 GPM covers most residential work, and 7 GPM makes roofs and taller walls easier. A 1 GPM pump is fine for spot treatment but slow for whole houses. If two operators share one system, step up to a gear driven pump.

How far will a 12 volt soft wash pump spray?

A healthy 5.5 to 7 GPM pump with the right tip and hose reaches 30 feet or more of vertical throw, enough for most two story homes from the ground. Reach depends as much on nozzle orifice and hose diameter as on the pump, so do not fight a small pump with a bigger tip.

Why does my 12 volt pump keep cycling on and off?

Rapid cycling means the demand switch is reacting to restriction: a partially closed valve, a kinked or undersized hose, a clogged tip, or a hose still coiled on the reel. Clear the restriction or add an accumulator. Constant cycling overheats the motor and kills the switch.

How long do pump diaphragms last?

With daily flushing, a gear driven pump usually goes a season or two of full time work before it wants diaphragms and valves, and kits cost far less than a new pump. Skipping the flush can wreck a diaphragm in weeks. Cheap 12 volt units are usually replaced rather than rebuilt.

Is a gas powered diaphragm pump worth it over 12 volt?

If you soft wash occasionally, no, a 12 volt does the job for a fraction of the price. If soft washing is a daily service, the gear driven pump earns its cost through higher flow, longer reach, and the ability to rebuild instead of replace.