The M-TD-11 has 2 sequential keys - one key trapped, one key free - actuator unlocked. When the actuator is unlocked the "access" key can be taken "on the person" into the guarded area without fear of the "trapped" key being removed and the equipment restarted. The M-TD-11 Tongue Interlock works on the principle that when the "access" key is "trapped" the actuator cannot be removed and is locked in position. Only when the "free" key from the Isolator or Key Exchange System is inserted into the second barrel can the "access" key be removed thereby allowing the actuator to be removed. Only when the isolator key is returned to the Isolator Switch can power then be re-applied to the guarded area. With a die-cast body with mirror polished finish the M-TD-11 Tongue Interlock is suitable for SIP and CIP cleaning processes with high pressure hosing with detergents at high temperatures.