Flow Switches are offered in a variety of flow metering technologies with a full range of "Flow/No Flow" switching options to help you select the most appropriate, cost-effective flow switch to fit your specific needs. These include:

• Vane Operated Flow Switches with field adjustable actuation switches
• Variable Area Flow Meters with direct reading flow scales and a variety of flow limit switches
• Ultrasonic (Doppler Flow Switch) with non-invasive ultrasonic sensors and adjustable flow/no flow control relays
• Thermal Dispersion (Thermal Mass) Flow Switches with solid state FET switching or relay controllers

Applications

These flow switches offer you the rugged reliability of time-tested flow-metering techniques with the automatic safeguard of protecting motors, pumps and other process equipment against damage due to low flow or no flow disruptions.

They automatically activate/deactivate electrical circuits to:

• Start auxiliary pumps and motors
• Actuate emergency alarms, sound buzzers, flash warning lights
• Shut off production machines, water-cooled engines or other process equipment when flow is interrupted
• Shut down burners, boilers or other process heaters if air flow fails

They can also automatically control flow in:

• Chemical Processing
• Heating/Refrigeration & Air Conditioning
• Machinery & Machine Tool
• Liquid Transfer
• Food Processing

Vane Operated Flow Switch

Vane Operated Flow Switch is a reliable mechanical device that uses the force of the fluid velocity exerted against a vane (a paddle mounted on a vertical pivot point) inserted into the flow stream to activate/deactivate an electric switch at a predetermined flow rate.

During normal flow operation (within the preselected flow range), the vane is held back, in the "off" position against the flow switch body. If flow drops below the preselected minimum flow rate, gravity allows the vane to drop to a vertical position. This activates an internal magnetic coupling and mechanical switch actuation lever, tripping an electrical switch to open/close an electrical control circuit.

The actuation/deactuation points are a function of the vane's surface area exposed to the flowing liquid, the cross sectional area of the flow stream and the characteristics of the fluid.

The Variable Area Flow Switch

Piston Type

Offered in a variety of construction materials, including: anodized aluminum, brass, stainless steel and high-impact resistant polysulfone, the EH55 Series Flow Switches feature a piston-type variable area flow meter with a direct reading flow scale and externally-mounted adjustable flow limit switches. This design uses the movement of the internal piston to activate/deactivate one of the following switching options:

• A single or double Microswitch (SPDT) to trigger a control relay
• A Reed Switch (AC) to trigger a TRIAC
• Or, a Hall Effect Sensor (DC) to trigger a MOSFET

The OC55-S Series Flow Switch is a simple piston-type variable area flow switch, offered in a choice of Polypropylene, Kynar (PVDF) or Acetal construction materials, with a hermetically-sealed glass reed switch to monitor the position of the piston-shaped magnetic poppet, housed in a right angle body mounting version as well as a straight in-line style.

The WD15-S5 Series Flow Switch is another simple piston-type variable area flow switch that utilizes a free moving shuttle to activate an isolated, sealed reed switch when it is displayed by the liquid flow. Mountable in any orientation, these switches can be used in media that is compatible with Noryl, GFN3, stainless steel and ceramic.

How it Works

Flow entering the inlet port creates a pressure differential across the magnetic poppet, causing it to move up through the meter body against the retaining spring. Movement continues until forces are balanced. When the flow rate reaches the preselected set point, the SPST switch closes. This is a "close on flow" low power switching device designed to switch resistive loads, such as solid state relays and programmable controllers.

Rotameter

The OK55 Series Flow Switches operate using the well known float system to provide both visual flow rate indication and monitoring capabilities for liquids and gases. Designed for vertical, upward flow applications, these switches are offered in either a brass or stainless steel version.

How it Works

As the flowing media moves upward, the meter's float is lifted to a level of equilibrium at which the weight of the float is equal to the upward force of the media. The upper edge of the float indicates the flow rate on the measuring glass. When the flow rate reaches the preselected set point, a permanent magnet contained in the the float actuates the reed switch.

Thermal Dispersion Flow Switch

The OF30-S Series is an insertion probe electronic mass flow meter which is offered with an optional fail safe controller for direct actuation of pumps, valves and blowers. It is also offered with a solid state FET (Field Effect Transistor) output for interface with remote PLC's or relay control devices.This type of solid-state electronic flow switch measures the temperature differential of the liquid or gas passing across the sensing elements to define the flow rate.

How it Works

Sensing Element A continuously measures the temperature of the flowing media, maintaining an appropriate temperature differential to element B. Element B is heated to a significant (i.e. 50 F) differential above Element A. As the flowing media passes over Element B some of the heat is transferred from Element B into the cooler flow stream. The rate of heat transfer is proportional to the mass velocity of the media. In other words, if the velocity increases, Element B will lose more heat. As Element B loses heat, more electrical energy is required to maintain the preset temperature differential between the two elements.

Ultrasonic Flow Switch

The EG50-S Series is a non-invasive flow switch, with a non-contact ultrasonic sensor that straps on to the outside of almost any pipe, from 0.5" to 180" diameter. This sensor transmits an ultrasonic signal into the flow stream while detecting the "doppler effect" frequency shift to measure the flow rate of "difficult" liquids, including: acids, caustics, chemicals, abrasives, waste water, sludge and other liquids that contain gas bubbles and/or suspended solids.The EG50-S Series Flow Switch is offered with adjustable actuation/deactuation set points from 1 to 10 ft/sec, as well as adjustable dead band, time delay and signal sensitivity.