EGE Flow Monitors

FLOW SENSORS

These devices monitor the flow of liquids, gases or granules. The operating principle is on thermal dispersion whereby the flowing medium extracts engendered heat from the sensor. If the flow rate drops below a pre-set threshold, the amount of heat extracted is reduced and the output is activated.

Features include:

• Detectors are temperature compensated to eliminate effects of temperature changes within the medium.
• Adaptable to temperature changes equivalent to a rate of 250°C/min.
• Sealed to a minimum of IP67.
• No moving parts such as floats or impellers which may jam or clog up after a period of time.
• Operation independent of density, temperature and pressure.
• Manufactured with British Standard Pipe threads for easy installation, and can simply be screwed into standard bosses or "T" pieces.
• EGE flow sensors can be used in hazardous areas. Approved by the PTB for use in both Zone 0 and Zone 1 Ex classified areas. 

Other housings are also available - such as NPT, or hygienic fittings for the food industry. Flange type mountings are also available for applications in the chemical industry.

As well as the standard stainless steel sensors, other more exotic materials can be used. EGE probes can be manufactured in a material to suit the customers requirements. Common types are bronze, hastelloy, Teflon and titanium. Corrosion resistance of the materials to be used must be specifically checked for the intended application.

• Manufactured in either 303 or 316 grade stainless steel.
• Either fixed cables or 'quick disconnect' type plug.
• Sensors can be mounted up to 100m away from the control amplifier.
• Sealing gasket supplied, alternatively PTFE tape can be used.
• Mediums can be monitored with temperatures from -20 to- +80°C (although versions are available for temperatures of up to 120'C).
• Supplied with either 1/4", 1/2" or 3/4" BSP sizes.
• Short versions available for direct mounting into "T" pieces.
• All standard sensors pressure tight up to 100 bar.

Special versions are available for applications such as high pressure. These are designed for static pressures up to 600 bar. Periodically fluctuating pressures up to 400 bar are admissible.

Special chemical resistant flow sensors are manufactured from titanium, with a metal-ceramic coating. This gives the sensors chemical resistance similar to Teflon or tantalum but with the same temperature behaviour as the standard stainless steel versions, namely a fast reaction time and a high temperature gradient.

Hygienic fittings are also available. These are mainly used in the food industry, particularly in dairy applications, where smooth surfaces and excellent cleaning capability are essential.

Design shape is adapted to the established DIN standard seals (DIN 11851) commonly known as a Tri-Clamp fitting. 

Long probe lengths can be specified for applications where large diameter pipe work is being used.

Probe lengths of up to 200mm can be supplied.

Many customers prefer a flange type fitting to the standard screw thread. These can be supplied to customer specified parameters. Standard material is 316 stainless steel; however, Hastelloy or Titanium are available for chemical applications.

Versions are available for use in zone 1 hazardous areas.

IN-LINE FLOW SENSORS 

In-line flow sensors fit into the pipe work using compression type fittings. This assures pressure resistance up to 10 bar. They are designed for use on pipes with diameters of 6, 10 or 12mm. The inside diameter of the sensor is smaller, resulting in a higher flow velocity through the sensor. They can detect flow rates down to 5ml/min.

The point of response for flow velocity is set at the switching amplifier. If the flow velocity is higher than the detection limit of the connected sensor, flow failure or reduction is displayed once the medium flow velocity has dropped back within the sensor detection range. 

These amplifiers are designed for fitting onto standard DIN rails.

They feature an LED line to give a visual indication of flow rates and for ease of setting. The red LED indicates that the flow relay is not activated. A yellow LED indicates that flow has just exceeded the set threshold value and the flow relay is activated. Four green LED's indicate that flow has exceeded the set threshold value by between 30 and 100%, and the flow relay is activated.

An additional output indicating temperature can be set by potentiometer. When the pre-set temperature is exceeded, the relay is activated and a red LED is displayed.

A time delay function is also standard on these units, adjustable between 0 and 25 seconds.

The slimline version is for DC operation. This device does not have the temperature or time delay functions. It offers the user a lower cost alternative when only a flow out-put is required, or when space in the panel is limited. 

• Encapsulated in solid housings.
• IP67 protection.
• Designed for exterior installation.
• LED line to give a visual indication of flow rates and for ease of setting.
• Optional temperature warning and time delay outputs.
• Access to adjustment pots by removal of clear plastic cover. 

These devices are manufactured in a one piece construction with the switching amplifier and sensor built into one housing. All of the adjustments are carried out via a pot on the rear of the probe.

• Sensors manufactured from 303 grade stainless steel for normal use, or titanium stabilised 316 stainless for agressive media.
• Probe lengths of up to 120mm can be supplied.
• LED line on rear of sensor for ease of setting up.
• Supply is 24VDC and output is a pnp normally open signal which can switch up to 400mA. 

The compact SN 450 range of flow sensors have a linear analogue 4-20 mA output. This provides the user with a measure of the flow velocity that can be calibrated. They are suitable for use when monitoring the flow of liquids. The probe must be positioned in the pipe in such a way that the tip is fully immersed in the medium.

With the largest flow, the instrument is set to an initial current of 20 mA by means of the trimming potentiometer. If there is no flow, the output current will be 4 mA. The largest detectable flow speed is 1.5 m/s. 

Many of the EGE flow sensors are approved for use in hazardous areas. Units are available for use in both Zone 1 and Zone 0 areas. Only sensors for which a certificate of conformity has been issued by the PTB can be used in Zone 0.

The sensor and the corresponding amplifier must be approved as a functional unit. Switching amplifiers that are not mentioned on the certificate must not be used. Our experts can advise you on the correct choice.

If sensors, or sensor cables need to be outdoors, a lightning protection unit must be installed. This accessory is inserted into the sensor line, between the sensor and the switching amplifier. It limits lightning-induced voltages on the sensor line and diverts them to earth.

Intrinsically safe switching amplifiers have galvanic separation between the intrinsically safe and non-intrinsically safe zones. The switching amplifier must always be mounted in the safe area. 

These devices are supplied as fully self-contained switches, designed for general purpose applications, such as ventilation ducts, where continuous automatic monitoring of air flow is required.

The function is also based on the calorimetric principle. If the gas flow stops, an electronic contact within the device opens or closes.

They are available for AC or DC circuits and are available in body sizes from dia. 20mm up to M38, and have a built in start up delay which cuts out after the operating-flow has been reached. 

These devices are manufactured from stainless steel and are designed for applications where the compact units are not suitable. This could be due to the aggressive nature of the gas to be monitored or where reaction times need to be faster.

These sensors can also be sealed into pipe work or ducting more adequately. Versions are also available with analogue (4-20mA) outputs where a measure of the flow velocity is required. These can also be supplied for use in Ex hazardous areas (Zone 1) when used with the PTB approved range of flow amplifiers.