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NRS™ Needle Control Valves

Low Flow Gas & Liquid Flow Control Valves
Models 8503D / 8504D

The Brooks® NRS™ (non-rising stem) control valves are designed specifically for extremely low flow gas and liquid applications. Straight and 90° angle pattern models in stainless steel are available. They feature a means of adjusting a sliding tapered needle which prevents sticking due to foreign matter in the fluid. These valves are particularly suitable for precise control requirements and possess a high turns to lift ratio. The flow is constant for any given stem position.

Six needles with different tapers provide a wide choice of flow ranges. Needles and orifices can be changed without removing the valve body from the line (two different orifices are used, one for needle sizes 1-3, another for sizes 4-6).


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  • Smooth non-reversing flow characteristics
  • Constant flow at any given stem position
  • Fifteen turns full open to full close provides high turn to lift ratio for excellent resolution
  • Six interchangeable needle tapers, each increases capacity by an approximate factor of three
  • O-ring seal cannot be damaged by overtightening
  • Panel mounting nuts included - standard
  • 1/8" NPT connections integrally machined into body

For Use With

  • Mass Flow Meters
  • Variable Area Flow Meters
Product Type

Designed for Extremely Low Flow Applications

Straight and 90° Angle Pattern Models Available

Wide Choice of Flow Ranges

Flow Range (Full Scale Capacity)
See Capacities & Pressure Drops Table in Data Sheet
Max Pressure
Stainless Steel Model: 1000 psig
Max Temperature
Stainless Steel Model: 250oF (120oC)
Connection Types

Standard: 1/8" female NPT - integral

Optional: 1/8", 1/4" compression fitting; 1/4" female NPT; 1/4" ID hose type adaptors

See Dimensions Figure
Materials of Construction

316 Stainless Steel

Size 1-3: Stainless steel and Teflon®;
Sizes 4-6: Stainless Steel

Valve Needle
316 Stainless Steel

Stainless Steel

Viton® fluoroelastomers

8503D 8504D
Configuration NRS Angle Pattern NRS In-line Pattern
FilenameFile TypeDocuments By Language
Data Sheet pdf English