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Rockford Systems, LLC—www.rockfordsystems.com
Call: 1-800-922-7533
DM
2
Series D Dual-Solenoid Valves
SECTION 2—OVERVIEW
INTRODUCTION
Mechanical power presses and other potentially hazardous machinery using a pneumatically controlled clutch and
brake mechanism must use a press control dual-solenoid valve with a monitoring device. The consensus requirements
of the regulations and good safety practices require that, in case of a failure within the valve, the clutch and brake
mechanisms be quickly exhausted, a monitor takes action to prevent further operation, and a method to alert person-
nel is incorporated.
The DM
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Series D dual-solenoid valve has two valve elements independently controlled by two solenoid pilots. The two
valve elements share common inlet, outlet, and exhaust ports. When the pilot valves are simultaneously energized, the
valve elements operate so that the valve functions as a 3/2 normally closed valve. If the valve elements fail to move
simultaneously, the dynamic monitoring of the valve detects this failure and thereby exhausts downstream air, locks
out the valve, and prohibits further operation. When a valve lockout occurs, the valve will retain the fault information
regardless of air or electrical changes. The system can only be reset by a defined operation/procedure, and will not self
reset (turn off and on), or reset when inlet air supply is removed and re-applied.
Valve element redundancy provides an additional safety factor, as the likelihood of a malfunction in both valve elements
in the same cycle is considered extremely remote. Therefore, a lockout condition is not necessarily an indication that
the valve has become faulty; rather, it is an indication that the monitor has detected nonsimultaneous movement of the
main valve elements, and that there is a condition in the system that needs correction.
For safety reasons, do not install any pneumatic devices between the valve and the clutch/brake or air cylinder,
including quick-dump valves.
If both valves fail simultaneously on the same stroke (cycle), this valve will not prevent a repeat stroke.
Never place the hands or any body part in the point of operation of this press at any time, for any reason.
