E0944
June 2015
Type EZL
Type EZL with 6350 Series Pilot and Type P590 Pilot Supply Filter
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
LOADING PRESSURE
Principle of Operation
Single-Pilot Regulator
The pilot-operated Type EZL (Figure 2 or 3) uses inlet
pressure as the operating medium, which is reduced
through pilot operation to load the actuator diaphragm.
Outlet pressure opposes loading pressure in the
actuator and also opposes the pilot control spring.
When outlet pressure drops below the setting of
the pilot control spring, pilot control spring force on
the pilot diaphragm thus opens the pilot valve plug,
providing additional loading pressure to the actuator
diaphragm. This diaphragm loading pressure opens
the main valve plug, supplying the required flow to the
downstream system. Any excess loading pressure on
the actuator diaphragm escapes downstream through
the bleed restriction in the pilot.
When the gas demand in the downstream system
has been satisfied, the outlet pressure increases.
The increased pressure is transmitted through
the downstream control line and acts on the pilot
E0944_06/2015
Figure 2.
Type EZL with Type 6352 Pilot
diaphragm. This pressure exceeds the pilot spring
setting and moves the diaphragm, closing the orifice.
The loading pressure acting on the main diaphragm
bleeds to the downstream system through a bleed
restriction in the pilot.
Monitoring Systems
Monitoring regulation is overpressure protection by
containment, therefore, there is no relief valve to vent
to the atmosphere. When the working regulator fails
to control the pressure, a monitor regulator installed
in series, sensing the downstream pressure, goes
into operation to maintain the downstream pressure
at a slightly higher than normal pressure. During an
overpressure situation, monitoring keeps the customer
on line. Also, testing is relatively easy and safe. To
perform a periodic test on a monitoring regulator,
increase the outlet set pressure of the working
regulator and watch the outlet pressure to determine if
the monitoring regulator takes over at the appropriate
outlet pressure.
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
LOADING PRESSURE
P590 SERIES PILOT
SUPPLY FILTER
“D” PORT
SENSE
PRESSURE
TYPE EZL MAIN VALVE
“A” PORT
INLET PRESSURE
“C” PORT
LOADING PRESSURE
TYPE 6352 PILOT
3
Type EZL
