Types 66, 66Z, and 66ZZ
D100247X012
Instruction Manual
Form 1056
November 2008
www.emersonprocess.com/regulators
Types 66, 66Z, and 66ZZ Pressure
Reducing Regulators
!
WaRning
Failure to follow these instructions or
to properly install and maintain this
equipment could result in an explosion
and/or fire causing property damage and
personal injury or death.
Fisher
®
regulators must be installed,
operated, and maintained in accordance
with federal, state, and local codes, rules
and regulations, and Fisher instructions.
if the regulator vents gas or a leak
develops in the system, service to
the unit may be required. Failure
to correct trouble could result in a
hazardous condition.
Call a gas service person to service
the unit. Only a qualified person must
install or service the regulator.
introduction
Scope of the Manual
This instruction manual provides instructions for
the installation, adjustment, and maintenance
of the Types 66, 66Z, and 66ZZ pressure
reducing regulators. Parts ordering information
is also provided. Other 66 Series regulators and
accessories are covered in other manuals.
Description
The Type 66 self-operated regulator (Figure 1)
maintains a reduced outlet pressure while satisfying
the downstream flow demands. The Types 66Z and
66ZZ self-operated regulators (Figures 8 and 9) also
control a reduced outlet pressure; however, both have
springs sensitive to negative pressures and can be
used for vacuum regulation. Each regulator type has
a balancing diaphragm which increases accurate and
sensitive response to pressure changes by reducing
the unbalanced forces acting on the valve plug. This
regulator and its installation should be checked for
compliance with all applicable codes.
Specifications
The Specifications table lists the specifications for
the Types 66, 66Z, and 66ZZ self-operated pressure
reducing regulators. Some of the specifications for a
given regulator as it comes from the factory appear on
the regulator nameplate.
Principle of Operation
The cast iron Type 66 regulator uses a pitot tube to
sense outlet pressure while the steel Type 66 regulator
uses an external control line to sense outlet pressure
as shown in Figure 6. Both pressure-sensing methods
register the outlet pressure under the main diaphragm.
When increased downstream demand lowers the outlet
pressure, the lower pressure under the main diaphragm
causes the regulator main spring and valve plug and
stem assembly to open the regulator seat ring and to
supply more gas to the downstream system.
W1935-1
Figure 1.
Type 66 Self-Operated Pressure
Reducing Regulator
