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Personal injury, equipment damage 

or leakage due to escaping fluid 

or bursting of pressure-containing 

parts may result if this regulator is 

overpressured or is installed where 

service conditions could exceed the 

limits given in the Specifications 

section, or where conditions exceed 

any ratings of the adjacent piping or 

piping connections.
To avoid such injury or damage, provide 

pressure-relieving or pressure-limiting 

devices (as required by the appropriate 

code, regulation or standard) to 

prevent service conditions from 

exceeding limits. 
Additionally, physical damage to the 

regulator could result in personal injury 

and property damage due to escaping 

fluid. To avoid such injury and damage, 

install the regulator in a safe location.

Clean out all pipelines before installation of the 

regulator and check to be sure the regulator has not 

been damaged or has collected foreign material during 

shipping. For NPT bodies, apply pipe compound to 

the external pipe threads. For flanged bodies, use 

suitable line gaskets and approved piping and bolting 

practices. Install the regulator in any position desired, 

unless otherwise specified, but be sure flow through 

the body is in the direction indicated by the arrow on 

the body.
Install Types 66, 66Z and 66ZZ regulators horizontally 

with the spring case vertically above the valve body.

Note

It is important that the regulator be 

installed so that the vent hole in the 

spring case is unobstructed at all times. 

For outdoor installations, the regulator 

should be located away from vehicular 

traffic and positioned so that water, ice 

and other foreign materials cannot enter 

the spring case through the vent. Avoid 

placing the regulator beneath eaves or 

downspouts, and be sure it is above the 

probable snow level.

With steel bodies, an external control line is required. 

Connect DN 20 / 3/4 in. NPT control line to the lower 

diaphragm casing connection from the point where the 

downstream pressure is to be sensed.

Overpressure Protection

The recommended pressure limitations are 

stamped on the regulator nameplate. Some type of 

overpressure protection is needed if the actual inlet 

pressure exceeds the maximum operating outlet 

pressure rating. Overpressure protection should 

also be provided if the regulator inlet pressure 

is greater than the safe working pressure of the 

downstream equipment.
Regulator operation below the maximum pressure 

limitations does not preclude the possibility of damage 

from external sources or debris in the line. The 

regulator should be inspected for damage after any 

overpressure condition.

Startup

The regulator is factory set at approximately 

the midpoint of the spring range or the pressure 

requested, so an initial adjustment may be required 

to give the desired results. With proper installation 

completed and relief valves properly adjusted, slowly 

open the upstream and downstream shutoff valves.

Adjustment

To change the outlet pressure, remove the closing 

cap or loosen the locknut and turn the adjusting 

screw clockwise to increase outlet pressure or 

counterclockwise to decrease pressure. Monitor 

the outlet pressure with a test gauge during the 

adjustment. Replace the closing cap or tighten the 

locknut to maintain the desired setting.

Taking Out of Service (Shutdown)

!

WARNING

To avoid personal injury resulting from 

sudden release of pressure, isolate 

the regulator from all pressure before 

attempting disassembly.

Parts List

Key Description

Valve Body

Upper Diaphragm Casing

Lower Diaphragm Casing

Diaphragm Plate

5* Diaphragm

6 Spring

Bottom Flange

8* O-ring

Disk Retainer

10 

Valve Plug Skirt

11 

Seat Ring

12 

Pitot Tube

13 

Valve Plug System

14*  Balancing Diaphragm

15 

Sealing Diaphragm Plate

16 

Diaphragm Spacer

17 

Lower Spring Seat, Types 66 and 66Z only

18*  Stem Gasket

19*  Bottom Flange Gasket

20 

Cap Screw

*Recommended spare part.

Types 66, 66Z and 66ZZ

2

Summary of Contents for FISHER 66

Page 1: ...ng Pressure Type 66 66Z or 66ZZ 0 55 bar 8 psig positive pressure 66 Series Vacuum Regulator 1 01 bar differential 14 7 psi or 29 9 in Hg vacuum 66 Series Vacuum Breakers 0 55 bar differential 8 psi or 16 3 in Hg vacuum Maximum Safe Pressure to Avoid Internal Parts Damage Type 66 66Z or 66ZZ 0 07 bar differential 1 psig above outlet pressure setting 66 Series Vacuum Regulator No more than 0 07 bar...

Page 2: ... 3 4 in NPT control line to the lower diaphragm casing connection from the point where the downstream pressure is to be sensed Overpressure Protection The recommended pressure limitations are stamped on the regulator nameplate Some type of overpressure protection is needed if the actual inlet pressure exceeds the maximum operating outlet pressure rating Overpressure protection should also be provi...

Page 3: ... Vent Assembly 31 Pipe Plug not shown 34 Washer 35 Gasket 36 Washer Types 66 and 66Z only 37 Sealing Washer 38 Counter Spring Type 66Z only 43 Spring Retainer Type 66ZZ only 44 Set Screw for Type 66 with external control line and adjustable travel stops 45 Hex Nut for Type 66 with external control line and adjustable travel stops 46 Adjusting Screw Cap for Type 66 with external control line and ad...

Page 4: ...he Emerson logo is a trademark and service mark of Emerson Electric Co All other marks are the property of their prospective owners Fisher is a mark owned by Fisher Controls International LLC a business of Emerson Automation Solutions The contents of this publication are presented for information purposes only and while effort has been made to ensure their accuracy they are not to be construed as ...

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