Q: I’m installing a conveying system outdoors, what options and features should I look for in my valves and gates?
A: Outdoor applications are the most demanding for pneumatic conveying equipment. Valves and gates installed outdoors must contend with extreme temperature changes, constant exposure to moisture, environmental pollutants, the sun, dust and dirt. Valves and gates not designed or modified for these conditions will definitely fail or require constant maintenance. Luckily most manufacturers have taken this into account and offer specifically designed valves and gates or special modifications/options to standard models to defend against pre-mature failure or extend the service life.
Since the valve will be exposed to the elements, the construction material is important. Valves and gates consisting of carbon steel parts will require painting to prevent rust. The painted surfaces must also be maintained to prevent/retard rusting. Valves and gates made from Stainless Steel and/or Aluminum will offer excellent corrosion resistance when exposed to the elements.
In addition to the material of construction, the method of construction is important. Valves and gates should feature sealed body construction to prevent ingress if water, dust and dirt when installed. This can be accomplished by utilizing a solid casting as the valve body or by sealing the components with gaskets and sealer during construction.
Another point of concern is the actuation options available. Valves will generally require powered actuation versus manual actuation since valves may be inaccessible or remotely controlled. Also, depending on construction, manual valves are often more susceptible to the environment especially if they have exposed threads or rods. Typically valves can be actuated via fluid power (Hydraulic or Pneumatic) or electrically. If located in a cold environment, fluid power is very susceptible to freezing if any moisture is present in the fluid. Various options exist which can be employed remove moisture from the fluid (desiccants, water separators, air driers etc.). Pneumatically actuated valves can also be equipped with a FRL (Filter, Regulator and Lubricator) which employs a special cold weather lubricant which contains antifreeze. Attention should also be given to the fluid power controls (solenoid valves etc) which will be used to control the valve and may be exposed to the environment. Solenoid Valves should bear an environmental rating suitable for outdoor applications.
If hydraulic or pneumatic actuation is not an option (extreme conditions, remote locations or lack of pneumatic or hydraulic supply) Electric actuation is an excellent alternative. Electric actuators will work in extreme conditions and are simple to install and control. Electrical Actuators specified for use outdoors should have a sealed construction which prevents ingress of water, dust and dirt into the internal mechanisms. The electrical connections and circuitry should be housed in a sealed enclosure which is rated for outdoor applications.
Electrical products such as solenoid valves and electrical actuators are generally certified under the National Electrical Manufacturers Association code (NEMA) and bear a NEMA rating (such as 4/4x) or by the International Electrotechnical Commission and bear an Ingress Protection Rating (IP) (such as IP65). Consult with the manufacturer for the environmental ratings offered and consult local codes and standards to determine the ratings required.
