Support For Kates Flow Rate Controller

How a Kates Flow Rate Controller Works
Controller Flow Rate Operation

A Kates Flow Rate Controller controls flow by maintaining a constant pressure differential across a metered orifice. The simplicity of its design begins with the Internal Differential Regulating Valve (IDRV).

When fully extended the IDRV will cover the exit port. When the inlet pressure is applied, the top of the impeller sees the upstream pressure, P1, and is forced down. Subsequently, fluid flows through the metered orifice resulting in an internal pressure, P2. Further pressure is dropped across the exit orifice resulting in the discharge pressure, P3.

The IDRV is in an equilibrium when the upstream pressure is reacted by the internal pressure plus the force of the spring. If the internal pressure is too low, then the IDRV will move down decreasing the area of the exit port. This will in turn increase the internal pressure. Thus the pressure across the impeller, as well as the metered orifice, is maintained to be constant. When the upstream pressure fluctuates, the internal pressure will adjust accordingly. When the downstream pressure fluctuates, the IDRV will adjust the size of the exit port to maintain the internal pressure.

The flow rate can be adjusted by changing the area of metered orifice. This is done through the control knob on the top of the flow rate controller.

With a Kates Flow Rate Controller, the user maintains flow to within 1-1/2% of the setpoint, regardless of pressure variations. Just set it and forget it!

Recommended Protection for
Kates Flow Controllers
Screening Rate
Strainer Filter
Controller Size Mesh Micron
1/2" 1600 14
3/4" 200 75
1-1/2" 150 100
2" 150 100
3" 150 100
4' 100 150

For long lasting maintenance free operation, we recommend that a strainer or filter be installed immediately upstream of the Kates.

The screen sizes listed are recommendations resulting from service experience. Obviously we cannot make operating guarantees because of the variety of fluid characteristics and the infinite number of combinations of particle size and nature encountered in practice. To obtain satisfactory results with a Kates Flow Rate Controller, the particles must be nonabrasive, non-fibrous, and must not adhere or coat on the controller internal parts, nor have a tendency to settle out of solution.

Technical Information on the Kates Flow Rate Controller

Accurate Flow Control Without a Flow Control Loop
To many engineers, accurate flow rate control infers a flow control loop or system. This system must include three or more distinct pieces of equipment, each piece containing one or more mechanical devices or linkages. Two or more transducings of any flow error signal are required, and the fluid characteristics of one or more Whaling and/or power media are involved. The entire system arrangement is fundamentally characterized by its use an orifice of fixed area as a sensor

In contrast, accurate flow rate control can be effected by a single control unit requiring no external cooperated equipment of any kind. No transducing of the original flow error signal is necessary. Since no external signaling and/or power media are involved, no characteristics of these affect operating characteristics of the control. The entire scheme is characterized- by its use of a flow setting orifice which is adjustable in area. A picture contrasting the two methods of control can be obtained most rapidly and clearly by starting with the basic fundamentals of the two schemes.

With Kates Adjustable Orifice the orifice area is adjustable. Pressure drop across the orifice is automatically maintained constant. Set point is changed by changing the orifice area.

The Idea

The Kates Flow Rate Controller uses an adjustable-area orifice as a sensory element. Pressure differential across this orifice is automatically maintained constant, regardless of the orifice area. Total flow rate is therefore directly proportion to orifice area. The orifice and automatic differential pressure regulator are enclosed in a single homing, with a calibrated flow-rate indicating dial.

The accuracy of the Kates Flow Rate Controller is complete accuracy of control as obtained in service; no external devices require consideration.

Deviation from set point depends on response of the differential pressure regulator, and is the same for all orifice openings. Translated into terms of service performance, this means that percent deviation from set point is the same at 20% of maximum how as it is at 30%, or at full scale.

For a wide range of combinations of fluids and fluid circuits, corrective action of the Kates Flow Control occurs in approximately one second. However, it is obvious that the corrective action of any control driven by power fray the fluid stream depends on die power source driving the stream, the fluid, and the fluid circuit characteristics. Therefore no universally attainable operating time can be stated. Operating time is inherently low, however, because there is no transducing of flow signals and because of the rigid connection of the force balance member to the corrective.

Adjustable Orifice Flow is directly proportional to orifice area. This gives a "straight-line" uniform scale, equally sensitive at high and low ends.

Advantages of the Kates Flow Rate Controller
  1. Automatically corrects for any changes to the inlet or outlet pressure to maintain the set point flow to +/-1.5% of setting.
  2. Flow is directly proportional to orifice area.
  3. "Straight-line" uniform linear scale.
  4. Accuracy by means of a self-operating single unit.
  5. No need for 10 - 20 straight runs of pipe diameter upstream or downstream to insure control accuracy.
  6. No electric, air or hydraulic connections are required.
  7. Large turndown ratio typical 25 to 1 or better.
  8. Fast acting.
  9. On liquid service, moving parts are immersed in the fluid which helps to prohibit hunting or oscillation.
  10. Simple design and few parts eliminate the many calibration and adjustment checks required of a typical flow rate control system.
  11. Capable of taking large pressure drops.
  12. Automatically takes whatever pressure drop is required to deliver the required flow.
  13. Cf & Cv are not a factor-Control set point is maintained as long as there is a minimum differential pressure of 10 psi between the inlet of the Kates and the outlet of the system.
  14. Sizing requires no formula's, It is only necessary to know the required flow and select the correct range.
  15. Low initial costs and low operating costs.
Kates Flow Rate Controller Maintenance

Under normal operating conditions, with a recommended strainer upstream that is properly maintained the Kates flow rate controller should perform many years without the need for changing parts. It would be expected that if wear would occur it would be on the adjuster shaft O-ring.

We recommend the purchase of a complete replacement parts kit. The kit includes all internal parts O-rings and a dial calibrated to the new parts. Thus, if any damage does occur to the controller, a new unit is available at a cost saving. Due to ongoing engineering & manufacturing changes we have found changing of individual parts will change calibration and in some cases parts will not be interchangeable. To avoid problems we offer only complete replacement parts kits when parts other than o-rings are required. Parts supplied in kit are as shown on the flow rate assembly drawing.

If you wish to try and clean the Kates instead of or before purchasing a complete replacement parts kit, follow the procedure indicated below.

To clean the Kates Flow Rate Controllers
  • Turn the unit all the way to the minimum flow setting.
  • Remove the body/bonnets bolts and mark the flanges.
  • Clean out any dirt or particulate and smooth out any gall marks with emery cloth.
  • Use the following assembly drawing if you feel you need to remove any of the internals to clean.
Flow Rate Controller