Series 110 Differential Control

Series 110 Differential Control

The Series 110 Differential Control Valve is designed to accurately control the pressure difference between any two points. In some systems this means the valve remains closed until pressure differential commands its opening. It is a pilot-operated, modulating type valve which controls pressure accurately and consistently at the desired setting.

Differential Control Valves

Valve Features

  • Operates automatically off line pressure.
  • Heavy-duty, nylon-reinforced diaphragm.
  • Rectangular-shaped, soft seat seal provides drip-tight Class VI closure.
  • Diaphragm assembly Guided top and bottom.
  • Throttling seat retainer for flow and pressure stability.
  • Easily maintained without removal from the line.
  • Replaceable seat ring.
  • Alignment pins assure proper reassembly after maintenance.
  • Valves are factory tested.
  • Valves are serial numbered and registered to facilitate replacement parts and factory support.

Pump Differential Control


Installed on the discharge side of a pump, the valve senses high pressure at pump discharge (valve inlet) and low pressure at the pump suction. Valve modulates to hold differential pressure constant, thus assuring pump is at optimum point on its curve.

Filter Bypass Control


In a filtered liquid application where loss of flow cannot be tolerated, the model 110 allows flow should the filter become clogged.

Valve Operation

  • Maintains a constant differential pressure between two points in a system.
  • Valve opens on increased differential.


The Model 110 consists of the following components, arranged as shown on the schematic diagram:

  1. Model 65 Basic Control Valve, a hydraulically-operated, diaphragm-actuated, globe or angle valve which closes with an elastomer-on-metal seal.
  2. Model 1356 Differential Pilot, a two-way, normally-closed pilot valve that senses differential pressure across its diaphragm and balances it against an adjustable spring load.  An increase in differential above the set point makes the open.
  3. Model 126 Ejector, a simple “tee” fitting with a fixed orifice in its inlet port. It provides the proper pressure to the diaphragm chamber of the main valve depending on the position of the differential pilot.
  4. Model 141-2 Flow Control Valve-needle valve that controls the opening/closing speed of the main valve.
  5. Model 159 Y-Strainer (standard on water service valves), the strainer protects the pilot system from solid contaminants in the line fluid.
  6. Model 141-4 Ball Valves (standard on water service valves, optional on fuel service valves), useful for isolating the pilot system for maintenance or troubleshooting.
  7. Model 155 Visual indicator (optional).




  • Accurate sensing of inlet pressure.
  • Normally closed, pressure differential to open.
  • Simple, single adjustment.
  • All parts replaceable while mounted on valve.
  • Rubber-to-metal seat for positive shut-off.
  • Large area diaphragm for quick, precise throttling.
  • Bronze and stainless steel construction.
  • Multiple spring ranges.


Pilot Materials
Low-Lead Bronze
Stainless Steel
Spring Ranges
5-30, 20-80, 65-180 psi


Pilot 1356

The Model 1356 Differential Pressure Pilot controls the amount of pressure in the upper chamber of the main valve (hence, the degree of opening or closing of the main valve). The pilot senses high pressure under its diaphragm and low pressure above its diaphragm. As the differential increases above the setting of the spring (adjustable), the pilot opens, decreasing the pressure in the main valve diaphragm chamber, allowing the main valve to open a proportionate amount.

Sense line locations. High pressure sensing is typically at the main valve inlet. Low pressure can be sensed at the valve outlet or at a field installed remote location.



Because the Model 110 typically controls the differential pressure, that particular parameter of the sizing equation is already defined. All that remains is to ensure the valve is large enough to handle the required flow within proper velocity limits.

where:  Cv = valve coefficient
Q = Maximum flow rate, gpm
sg = Liquid specific gravity (water = 1.0)
dp = Differential pressure, psig

From the chart below, pick the smallest valve that has a Cv at least equal to the value calculated and where the velocity does not exceed 25 ft/sec.



Valve Selection Guide

By combining various control pilots, multiple valve functions can be performed on a single Series 110 Differential Control Valve. To find the combination function valve, select the desired features and then the model number.

This chart shows only a sample of those most often specified valves. Consult the factory for specific data on the model you selected.


Material Specifications




For maximum efficiency, the OCV control valve should be mounted in a piping system so that the valve bonnet (cover) is in the top position. Other positions are acceptable but may not allow the valve to function to its fullest and safest potential. In particular, please consult the factory before installing 8″ and larger valves, or any valves with a limit switch, in positions other than described. Space should be taken into consideration when mounting valves and their pilot systems.

A routine inspection & maintenance program should be established and conducted yearly by a qualified technician. Consult our factory @ 1-888-628-8258 for parts and service.



When Ordering please provide:
Series Number – Valve size – Globe or Angle – Pressure Class – Screwed, Flanged, Grooved – Trim Material – Adjustment Range – Pilot Options – Special needs / or installation requirements.