Valves in the Cleaning Industry

Written by Barry Victor, Founder of PROS Parts

Virtually every machine in the laundry and dry-cleaning industry utilizes valves for the control of fluids. Fluids can be defined as substances that have no fixed shape and so include gases like steam, air, natural gas and propane. Other fluids that valves are called on to control are water, solvent, oil and detergents and other chemicals.

PROS Parts has a strong distributor relationship with Asco Valves and we offer many types of valves for the control of these fluids. Asco has a very broad range of valves that can handle extremes of temperature and pressure as well as corrosive chemicals and explosive gases. They are available with operation by electrical current by a solenoid or alternately with pressurized air. Today I would like to talk about the most common type of valve used in the industry which is the solenoid operated steam valve.

Solenoid Operated Steam Valves

Asco has a broad array of solenoid operated steam valves. These valves are typically designed with brass bodies, Teflon seals and high temperature insulation on the solenoid coil to withstand the high temperatures. They are made to accommodate many different control circuit voltages to match the designer’s parameters as well as many different pipe sizes to accommodate different flow rates. They are normally closed to the flow of fluid and upon energization open to allow the full flow of the fluid.  This type of valve is available in a piston or diaphragm style.

Piston or Direct Operated

In these valves, the core is mechanically connected to the disc and opens or closes the orifice, depending on whether the solenoid coil is energized or de-energized. Core-disc valve construction (Fig. 2). Operation is not dependent upon line pressure or rate of flow (zero or maximum rated pressure). These valves are generally available in 2/2 NC/NO and 3/2 NC/NO/U versions.

Diaphragm or Pilot Operated

These valves use the inlet pressure (or full line pressure) for operation. They have two orifices (pilot and bleed). When the solenoid is energized, the pilot orifice is opened to release pressure from the top of the diaphragm (or piston) to the outlet side of the valve. The resulting difference in pressure causes the main orifice to open. When the solenoid is de-energized, the pilot orifice is closed and the full line pressure is applied to the top of the diaphragm (or piston) through the bleed orifice, providing seating force for tight closure.

Each of these valve types has benefits and drawbacks.

Speed – the opening and closing speed of the direct acting valve is much faster than the pilot operated valve. While speed can be beneficial in some applications, it is not as important in the control of steam in laundry machinery, and can actually be a detriment. If the valve is controlling a steam heating coil for example, the rapid open/close cycle of a direct operated valve can cause water hammer issues within the coil leading to premature coil failure. The pilot operated valve has a slower open/close speed and therefore is easier on the steam coil.

Purity – the direct operated valve is usually very forgiving with regard to impurities in the fluid flow since it has only one large opening for the fluid flow while the pilot operated valve has a fairly high requirement for purity of the fluid due to the small pilot hole paths.

Flow – generally the pilot operated valve has the better flow characteristic of the two types of valves.

Life – because all of the power to open and close the valve in a direct operated valve comes from the solenoid, they typically draw more power and run hotter than the coil of a pilot operated valve. This has the benefit of prolonging the life of the pilot operated valve.

PROS Parts is here for your valve needs – for parts and also for questions or information you may need,  please visit our  website or call 1-800-359-0628.

About Barry Victor

Barry founded PROS Parts in the spring of 1988. Before starting PROS, Barry worked in the sales and engineering departments of Vic Manufacturing, one of the largest manufacturers of dry cleaning equipment in the U.S. At Vic, Barry launched a parts sales division that supported dry cleaning equipment imported from Italy and Germany. In its early years, PROS manufactured dry cleaning machinery and then evolved into an industrial and commercial laundry equipment and dry cleaning operations parts supplier. Barry lives in Eden Prairie, MN with his wife. He has two sons, a step son, a step daughter and his dog, Sora. 

Barry can be reached at 763-231-7379 or barryv@prosparts.com.