Instruction Manual
D100348X012
2625 and 2625NS Volume Booster
January 2015
2
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 you use the volume booster only with an actuator, for on‐off control, the integral bypass restriction
on the volume booster must be closed (turned fully clockwise).
To facilitate diagnostic testing, you can install connectors and piping with each 2625 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 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.
