Instruction Manual
D100348X012
2625, 2625SST, and 2625NS Volume Booster
Fisher™ 2625, 2625SST, and 2625NS Volume
Boosters
May 2017
Contents
Introduction 1.................................
Scope of Manual 1..............................
Description 2..................................
Specifications 2................................
Educational Services 3...........................
Installation 4..................................
Mounting 5..................................
Pressure Connections 5........................
Diagnostic Connections 6......................
Supply Pressure 7.............................
Exhaust Ports 7...............................
Operating Information 7.........................
Principle of Operation 8.........................
Maintenance 8.................................
Diaphragm Assembly Replacement 8.............
Valve Assembly Replacement 9..................
Installation of Diagnostic Connections 10.........
Parts Ordering 11...............................
Parts Kits 11...................................
Parts List 11...................................
Introduction
Figure 1. Fisher 2625 Volume Booster
W4727-1
Scope of Manual
This instruction manual provides installation, operation, maintenance, and parts information for Fisher 2625,
2625SST, and 2625NS volume boosters (figure 1). Refer to separate instruction manuals for information regarding the
valve body, actuator, and other accessories.
Do not install, operate, or maintain a 2625, 2625SST, or 2625NS volume booster without being fully trained and
qualified in valve, actuator, and accessory installation, operation, and maintenance. To avoid personal injury or
property damage, it is important to carefully read, understand, and follow all of the contents of this manual, including
all safety cautions and warnings. If you have any questions regarding these instructions contact your Emerson sales
office or Local Business Partner before proceeding.
www.Fisher.com
2625, 2625SST, and 2625NS Volume Booster
May 2017
Instruction Manual
D100348X012
Description
The 2625 and 2625SST are certified for use in Safety Instrumented System (SIS) applications. Certification is by EXIDA
Consulting LLC, a global provider of functional safety and control system security. SIS certification is identified on the
product by the EXIDA logo on the 2625 nameplate.
The 2625, 2625SST, and 2625NS volume boosters are used in conjunction with a positioner on a throttling control
valve to increase stroking speed. The booster has a fixed deadband (controlled by the seat‐to‐seat dimension of the
supply and exhaust plugs) which is factory set during assembly and testing. In addition, the booster incorporates
soft‐seat construction and an integral bypass restriction to eliminate positioner saturation problems that can occur
with volume boosters that do not have these features. Adjustment of the integral bypass restriction is necessary for
system stability. This adjustment does not affect the deadband of the booster, but does permit the control valve to
respond to small input signal changes from the positioner without sacrificing steady‐state accuracy.
It also allows the booster to deliver high‐volume output for fast stroking when large, rapid input signal changes occur.
The volume booster is used to improve stroking speed. If precision valve control is required, the use of a positioner is
recommended. If the volume booster is used for on/off control, the integral bypass restriction on the volume booster
must be closed (turned fully clockwise).
To facilitate diagnostic testing, connectors and piping may be installed with each 2625, 2625SST, and 2625NS volume
booster.
The 2625NS volume booster is designed for nuclear power applications. The 2625NS construction includes materials
that provide superior performance at elevated temperature and radiation levels.
The O‐rings in the 2625NS are EPDM (ethylene propylene) and the diaphragms are EPDM/meta‐aramid. EPDM
demonstrates superior temperature capability and shelf life over nitrile. The meta‐aramid diaphragm fabric
demonstrates improved strength retention at elevated temperature and radiation conditions.
CAUTION
Use a clean, dry, oil‐free air supply with instruments containing EPDM components. EPDM is subject to degradation when
exposed to petroleum based lubricants.
Under the 10CFR50, Appendix B, quality assurance program, the 2625NS volume booster is qualified “commercial
grade dedicated”. These can be supplied as 10CFR, Part 21 items.
Specifications
Specifications for the 2625, 2625SST, and 2625NS volume booster are listed in table 1. Information for an individual
unit as it comes from the factory appears on the product nameplate.
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Instruction Manual
D100348X012
Table 1. Specifications
2625, 2625SST, and 2625NS Volume Booster
May 2017
Port Diameters
(1)
Supply Port: J 9.5 mm (0.375 inch) or J 12.7 mm
(0.5 inch)
Exhaust Port: J 2.4 mm (0.094 inch)
(2)
, J 9.5 mm
(0.375 inch) or J 12.7 mm (0.5 inch)
Input Signal
Positioner output
Maximum Input Signal Pressure
10.3 bar (150 psig)
Input to Output Pressure Ratio
Fixed at 1 to 1
Operative Temperature Limits
2625/2625SST
Standard: -40 to 71_C (-40 to 160_F)
High Temperature: 0 to 121_C (32 to 250_F)
2625NS: -40 to 93_C (-40 to 200_F)
Maximum Flow Coefficients
See table 2
Connections
Input Signal: 1/4 NPT
Supply and Output Signal: 3/4 NPT
Hazardous Area Classification
Complies with the requirements of ATEX Group II
Category 2 Gas and Dust
Supply Pressure Ranges
(3)
When used in conjunction with a positioner or other
pneumatic accessory, always pipe the positioner and
booster with one common supply through a Fisher
67D, 67DR, or MR95H regulator (see figure 3). A
Safety Instrumented System Classification
SIL3 capable - certified by exida Consulting LLC
high‐capacity filter, such as the Fisher 262K, should
be installed in the supply line to the regulator. Supply
pressure also must not exceed the maximum
pressure rating of the actuator. Constructions are
available in two maximum supply ranges.
When Normally Used With Diaphragm Actuators: Up
to 2.8 bar (40 psig)
When Normally Used With Piston Actuators: Up to
10.3 bar (150 psig)
Nominal Deadband
Percent of Positioner Output Span
(4)
(5)
:
2.4 mm (0.094 inch) exhaust port: 2%
9.5 mm (0.375 inch) exhaust port: 3.5%
12.7 mm (0.5 inch) exhaust port: 5%
1. May be used in any combination.
2. Aluminum 2625 volume booster only.
3. The pressure/temperature limits in this document, and any applicable code or standard limitation should not be exceeded.
4. This term defined in ISA Standard S51.1
5. Zero psig to maximum supply.
Approximate Weight
Aluminum: 2.3 kg (5 pounds)
Stainless Steel: 4.8 kg (10.6 pounds)
Declaration of SEP
Fisher Controls International LLC declares this
product to be in compliance with Article 4 paragraph
3 of the PED Directive 2014/68/EU. It was designed
and manufactured in accordance with Sound
Engineering Practice (SEP) and cannot bear the CE
marking related to PED compliance.
However, the product may bear the CE marking to
indicate compliance with other applicable EC
Directives.
(3,4)
Educational Services
For information on available courses for 2625, 2625SST, and 2625NS volume boosters, as well as a variety of other
products, contact:
Emerson Automation Solutions
Educational Services - Registration
Phone: 1-641-754-3771 or 1-800-338-8158
E-mail: education@emerson.com
emerson.com/fishervalvetraining
3
2625, 2625SST, and 2625NS Volume Booster
May 2017
Instruction Manual
Table 2. Maximum Flow Coefficients
PORT SIZE COMBINATIONS
Supply Port Exhaust Port
mm Inch mm Inch C
9.5 0.375
12.7 0.5
FIELDVUE™ DVC6200, DVC6200 SIS, DVC6200f, DVC6200p, DVC6000, DVC6000 SIS,
DVC6000f digital valve controllers
FIELDVUE DVC2000 digital valve controller
Low Pressure Relay
High Pressure Relay
Fisher 3570 valve positioner 0.25 0.25
Fisher 3582 valve positioner 0.17 0.19
Fisher 3610J, 3610JP, 3611JP, 3620J, 3620JP, 3621JP valve positioner 0.37 0.30
2.4
9.5
12.7
2.4
9.5
12.7
0.094
0.375
0.5
0.094
0.375
0.5
SUPPLY PORT COEFFICIENTS EXHAUST PORT COEFFICIENTS
v
3.74
3.74
3.74
4.98
4.98
4.98
0.37 0.31
0.13
0.19
Installation
D100348X012
C
v
0.23
2.29
3.40
0.24
2.30
3.40
0.15
0.20
WARNING
Always wear protective clothing, gloves, and eyewear when performing any maintenance procedures to avoid personal
injury.
System damage may result if a volume booster is installed in a way that it can be physically damaged.
Personal injury or system damage may result when service conditions exceed booster or other equipment ratings.
Exceeding the pressure specifications in table 1 may cause leakage, parts damage, or personal injury due to bursting of
pressure‐containing parts or explosion of accumulated gas.
Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.
CAUTION
Do not use sealing tape on pneumatic connections. This instrument contains small passages that may become obstructed
by detached sealing tape. Thread sealant paste should be used to seal and lubricate pneumatic threaded connections.
Note
Do not use separate pressure supplies for the volume booster and associated positioner.
The volume booster may not exhaust immediately upon loss of a separate pressure supply. However, if the system is in a transient
state at the time of pressure supply loss or if changes to the booster's input signal are sufficient to overcome the deadband, the
booster will exhaust.
A loss of a pressure supply (either separate or common) to a 3582 or 3610J positioner will cause the positioners output pressure
(booster's input pressure) to decay.
Always pipe the positioner and the volume booster with one common supply. See figure 3 for typical installation
examples. A 67D, 67DR, or MR95H regulator is required to provide sufficient capacity to supply both components. A
high‐capacity filter, such as the 262K, should be installed in the supply line to the 67D, 67DR, or MR95H regulator.
4
Instruction Manual
D100348X012
2625, 2625SST, and 2625NS Volume Booster
May 2017
Mounting
The volume booster is typically nipple‐mounted between the pneumatic supply source and the actuator, and may be
used with piston or diaphragm actuators. Many actuators require larger casing or cylinder connections and
modifications to allow the booster to deliver the higher volume output.
The booster may also be directly mounted to the actuator by using an actuator yoke mounting bracket (see figure 5)
or casing mounting bracket.
Pressure Connections
CAUTION
Do not use sealing tape on pneumatic connections. This instrument contains small passages that may become obstructed
by detached sealing tape. Thread sealant paste should be used to seal and lubricate pneumatic threaded connections.
The input signal connection is 1/4 NPT. The supply and output connections are 3/4 NPT (minimum pipe size
recommended for nipple mounting is 1/2 NPT for 2625 and 3/4 NPT for 2625SST). Connections to the volume booster
should be made as indicated in figure 2. Connections for two typical applications are shown in figure 3. Ensure that the
piping is of proper size to meet the capacity demands of the booster and that you equip the actuator with properly
sized input connections.
Figure 2. Volume Booster Sectional View
DIAPHRAGMS
(KEY 5 AND 6)
EXHAUST PORT
EXHAUST
SUPPLY
INPUT SIGNAL
BYPASS RESTRICTION
ADJUSTING SCREW
BYPASS RESTRICTION
(KEY 11)
SUPPLY PORT
OUTPUT TO ACTUATOR
W0679‐1
5
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