Proportional Control Metering Pump

The AT3-AM metering pump is designed to dose proportional to either a pulsed input signal or a 4-20mA input signal which automatically regulate the output flow rate of the dosing pump.

AT3-AM Proportional Metering Pump Introduction

The AT3-AM is a proportional control chemical metering pump which is designed to precisely meter chemical reagents into a process. The AT3-AM has a number of operating modes:-

• Constant flow rate - where the chemical delivery is set manually using the front mounted dial
• Proportional to a pulsed input signal - this can come from a water meter or compatible instrument, such as our P7685, P7687 or P6587
• Proportional to a 4-20mA output - supplied from a compatible instrument or process controller

When operating in proportional mode, the external control signal automatically varies the frequency or number of strokes the dosing pump makes per minute. This allows the pump to increase or decrease the flow rate, depending upon the instruction from the instrument - ideal for flow proportional dosing or pH correction applications.

The AT3-AM can be started / stopped from a volt free input, which is designed to operate as a low level cut-off.  The volt free input can be connected to an optional Low Level Float Switch or Suction Lance Assembly to prevent the pump from running when a low chemical level is present. The low level cut-off can be used in all operation modes.

In addition to the low level cut-off,  the AT3-AM includes a flow verification input from an optional flow sensor and a volt free alarm output.  This can be used to output to either some control equipment or an indicator if the dosing pump enters an alarm condition.

The AT3-AM can be attached to a flat vertical surface for surface mounting installation or used with the optional foot-mounting bracket for foot mounting applications.  Designed primarily for water treatment, wastewater treatment, effluent treatment and process control, the AT3-AM is a simple and reliable dosing pump for high pressure dosing applications.

The AT3-AM is powered from a switch mode power supply suitable for a mains supply of 100 - 240 VAC 50hz or 60Hz and is designed to IP65 specification.

AT3-AM Dosing Pump Outputs

The AT3-AM dosing pump series are available with the following outputs:-

AT3-AM - Manual Control

The AT3-AM has a number of operating modes, each of which is simple to setup and integrate into a process.  The AT3-AM can be used in a manual operation mode (although our AT3-BX or AT3-BL models maybe more appropriate), by switching the selector switch. The output of the pump can then be controlled using the front mounted potentiometer across 0 - 100% of the rated output.

AT3-AM - Proportional to Pulsed Input / Flow Proportional Dosing

The AT3-AM is designed to accurately meter chemical into a process vessel or pipework proportional to a pulsed input signal. This volt free input signal can be supplied from a water meter or a process controller which provides a pulsed output such including our P7687 and P6587 pH controllers.

When dosing proportional to the flow from a water meter, the water meter provides pulses based on the measured flow rate, eg. 1 pulse per litre.  As the flow rate increases or decreases, the number of pulses which are transmitted to the dosing pump increase or decrease, causing the dosing rate to increase or decrease to allow the dosing pump to maintain an even delivery of chemical into the flow.  This instrument is ideal for both water treatment and boiler dosing applications.

When dosing proportional to a process controller, the instrument will supply a pulsed output to the dosing pump.  This causes the pump speed or number of strokes per minute to increase or decrease proportionally.  The benefit of this is that the chemical reagent is delivered more quickly the further away from the setpoint and a smaller amount as it approaches the setpoint, reducing chemical usage and minimising the risk of over-dosing.

To ensure compatibility with a wide range of external equipment, the AT3-AM can multiply or divide the incoming pulses. The following multiplication and division modes are available:-

• 1:1 mode - where 1 pulse from the control equipment results in 1 stroke of the pump
• 4:1 mode - where 4 pulses from the control equipment results in 1 stroke of the pump
• 10:1 mode - where 10 pulses from the control equipment results in 1 stroke of the pump
• 1:n mode - where 1 pulse from the control equipment results in n strokes of the pump. N can be any number from 1 - 10 and is set using the front dial

In 1:n dosing mode, at the first signal received the AT3-AM will make n strokes at the maximum speed.  The AT3-AM will then measure the time between the successive pulses (maximum period of 60 seconds) and distribute the strokes evenly across the time period to ensure consistent dosing.

AT3-AM Dosing Pump Proportional to a 4-20mA signal

In addition to dosing proportional to a pulsed input signal, the AT3-AM is a 4-20mA proportional dosing pump, allowing the pump speed to be automatically regulated.

With a 4-20mA input, the AT3-AM will automatically stop when the signal is 4mA.  When the signal is 20mA the pump will dose at the percentage of the output selected by the top mounting dial.  The 20mA value or maximum value can be selected across a range of 10 - 100% of the pumps rated output.

AT3-AM Flow Verification, Level Input and Alarm Output

The AT3-AM includes a number of inputs which can be incorporated into normal pump duty if required, each of the inputs enter the pump into an alarm condition which stops the pump from operating and can be set to trigger an alarm output.

The alarm output is a volt free contact which can be used to trigger audible alarms, beacons, or feedback into an instrument, BMS system or PLC as required.

The low level input is designed to be triggered from an optional Suction Lance Assembly or a Low Level Float Switch preventing the pump from operating when a low chemical level is present.  The low level input is a volt free input it can trigger the alarm relay which can be wired to external equipment.

The flow verification input is designed to work with an optional flow sensor.  The flow sensor compares the output from the pump with the number of strokes that the pump makes.  If the flow sensor fails to measure a chemical reagent triggering the flow sensor after 6 strokes then it will trigger the alarm relay output.

AT3-AM Wetted Parts / Liquid End

The AT3-AM is designed as a chemical metering pump for industrial usage and as such has wetted parts developed specifically for chemical handling.

As standard, the AT3-AM is available with a liquid end manufactured in either PVC or PVDF, with Ceramic or PTFE balls and a PTFE diaphragm. The seals and O-rings are available in either Viton (© DuPont / Chemours) or EPDM with PTFE O-rings available as an option.

Our chemical compatibility database can be used to check the wetted parts.  Please don't hesitate to get in touch if you are unsure.

Priming the liquid end for dosing couldn't be simpler.  The AT3-AM is supplied with tubing and has an adjustable bleed valve located on the pump head.  Loosening the bleed valve allows the chemical reagent to be circulated through the pump quickly and easily to ensure accurate dosing.

What's in the box with the AT3-AM?

The AT3-AM is supplied complete with everything required to begin metering chemical reagents into a process.

Supplied with the dosing pump itself are:-

• Injection Valve with 3/8" and 1/2" BSP male threaded connections
• Foot-valve & Strainer assembly
• 1 metre of discharge tubing
• 2 metres of suction / bleed tubing
• Surface mounting kit

An optional foot mounting bracket can be included for no additional charge, if requested.

AT3-AM Features & Benefits

The AT3-AM is a robust, reliable and accurate chemical dosing pump, designed to operate continuously and proportional to an external signal.  The AT3-AM is ideal for either stand alone operation or integration with process control equipment such as a process controller or water-meter.  Designed to IP65 specification, the AT3-AM is ideal for use either inside or outside.

The AT3-AM makes commissioning the metering pump as simple as possible.  The 4-20mA output can be regulated using the front mounted dial and the pulsed input signal can be either multiplied or divided as required, to ensure full compatibility with most processes.  The AT3-AM is self priming and using the adjustable bleed valve ensures that this is accomplished swiftly and cleanly.

There are a number of additional safety measures on the AT3-AM, including the volt free input which can be used with an optional Low Level Float Switch or Suction Lance Assembly and the flow verification input (for use with an optional flow sensor) which will automatically stop the dosing pump from operating in the event of a low chemical level or if the output flow is not being measured.  Both of these options can be set to trigger the alarm relay output which can be directly connected to an indicator such as an audible alarm, a BMS or PLC or directly into another of our proportional control dosing pumps, where two or more pumps are being used in tandem. The alarm functionality can also be disabled completely if required.

The AT3-AM is designed specifically for chemical dosing with the wetted parts suitable for many chemical reagents.  The liquid end manufactured in PVC or PVDF, a PTFE diaphragm, with Ceramic or PTFE balls and either Viton, EPDM or PTFE seals and O-rings. Our chemical compatibility database can be used to ensure that the wetted parts are compatible with your chemical reagent.

The AT3-AM is available as the following model types:-

• AT3-AM-16-07 for an output flow rate of 7.0 Litres / Hour at 16 Bar pressure
• AT3-AM-10-10 for an output flow rate of 10.0 Litres / Hour at 10 Bar pressure
• AT3-AM-08-14 for an output flow rate of 14.0 Litres / Hour at 8 Bar pressure
• AT3-AM-02-18 for an output flow rate of 18.0 Litres / Hour at 2 Bar pressure

As the AT3-AM series are powered from a switch mode power supply and able to accept a mains supply of 100 - 240 VAC at 50Hz / 60Hz the AT3-AM suitable for export markets.

As part of our Red Dosing Pump range, the AT3-AM is rated hot for continuous dosing duty, and the pump is designed to provide a long trouble free life of accurate chemical dosing.