August 30, 2015 |
According to Humphrey Products Corporation, maker of the world-famous Humphrey Valve, Proportional valves are becoming a popular choice for machine and device builders looking for more flexibility. Proportional valves respond to variations in current applied to the solenoid by delivering a corresponding variable flow output.
The most popular and cost effective type of proportional valves have an armature that responds to changes in voltage or ampurage. This works against the force of a specially designed return spring. If coil and spring force were the only forces to be considered within the valve, precise output flow control can be achieved relatively easy.
But there are other forces at work here. One such force is simple friction, which is more difficult to control. Over time, the friction factor changes and thus the output of the valve changes as well. Even friction of just micrograms will affect the response time, along with the amount the armature moves inside the system, limiting the preciseness of a flow or pressure control.
Besides friction, air flow, air pressure and contaminates can also affect the response and movement of the armature. Air flow also creates friction on the system whether it is pushing force trying to open or hold close the orifice. Then once the orifice opens, it creates a pressure drop on the opposite side giving the system more to compensate for. These types of friction correlate to the effective response time and preciseness of the control that your proportional valve performance.
Manufacturers attempt to minimize or eliminate as much friction within proportional valves as possible to achieve consistent and reliable performance. When specifying proportional valves, users should consider the amount of friction potential for best results.
For more information, contact:
Diffley-Wright Exclusive Florida distributors for the Humphrey Valve & Products