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Proportional Control Dosing Pump

Proportional control metering pump AT2-AM for 4-20mA or pulsed input

The AT2-AM dosing pump will dose proportionally to either a 4-20mA or pulsed input signal, to automatically vary the speed or frequency of the dosing pump.

AT2-AM Proportional Control Dosing Pump Introduction

The AT2-AM is a proportional control chemical dosing pump which is designed to precisely meter chemical reagents into a process.  The AT2-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.  The AT2-AM is deal for flow proportional dosing or pH correction applications.

The AT2-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 low level cut-off,  the AT2-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 control equipment or an indicator, if the dosing pump enters an alarm condition.

The AT2-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, waste-water treatment, effluent treatment and process control, the AT2-AM is a simple and reliable dosing pump for high pressure dosing applications.

The AT2-AM is powered from a switch mode power supply which is suitable for a mains supply of 100 - 240 VAC 50hz or 60Hz and is designed to IP65 specification.

AT2-AM Dosing Pump Outputs

The AT2-AM dosing pumps are available with the following outputs:-

Model Number*Output (Litres / Hour)Pressure (Bar)Speed (Strokes / Min)Output (mls / stroke)Hose Size (mm)Power (Watts)
AT2-AM-12-03 0 - 3.0 12.0 160 0.31 4 x 6 15
AT2-AM-10-04 0 - 4.0 10.0 160 0.41 4 x 6 15
AT2-AM-08-05 0 - 5.0 8.0 160 0.52 4 x 6 15
AT2-AM-02-08 0 - 8.0 2.0 160 0.83 4 x 6 15

AT2-AM - Manual Control

The AT2-AM has a number of operating modes each of which is simple to setup and integrate into a process. The AT2-AM can be used in manual operation mode (although our AT2-BX or AT2-BL models may be 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.

AT2-AM Proportional to Pulsed Input / Flow Proportional Dosing

The AT2-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 as 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 makes it ideal for 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 AT2-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 AT2-AM will make n strokes at the maximum speed.  The AT2-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.

AT2-AM Dosing Pump Proportional to a 4-20mA signal

In addition to dosing proportional to a pulsed input signal, the AT2-AM is a 4-20mA proportional dosing pump, allowing the pump speed to be automatically regulated.

With a 4-20mA input, the AT2-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.

AT2-AM Flow Verification, Level Input and Alarm Output

The AT2-AM includes a number of inputs which can be incorporated into the normal pump duty if required.  Each of the inputs enters 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 volt free and 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 by triggering the flow sensor after 6 strokes, then it will trigger the alarm relay output.

AT2-AM Wetted Parts / Liquid End

The AT2-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 AT2-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.

  • Head Material

    The wetted parts of the pump head are manufactured in PVC or PVDF.

  • Double ball valves

    Double union ball valves are manufactured in PVC or PVDF with Ceramic or PTFE balls 

  • Diaphragm

    The diaphragm is manufactured in PTFE.

  • Injection Valve

    The injection valves are manufactured in PVC or PVDF

  • Foot Valve & Strainer Valve

    The foot valve and strainer assembly is manufactured in PVC or PVDF

  • Seals & O-Rings

    The seals and O-Rings are manufactured in VitonEPDM or PTFE.

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 AT2-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 to quickly and easily to ensure accurate dosing.

What's in the box with the AT2-AM?

The AT2-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.

AT2-AM Features & Benefits

The AT2-AM is a robust, reliable and accurate chemical dosing pump, designed to operate continuously and proportional to an external signal.  The AT2-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 AT2-AM is ideal for locating either internally or externally.

The AT2-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 AT2-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 AT2-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, if two or more pumps are being used in tandem.  The alarm functionality can also be disabled completely, if required.

The AT2-AM is designed specifically for chemical dosing and the wetted parts, suitable for many chemical reagents, with a liquid end manufactured in PVC or PVDF, a PTFE diaphragm, Ceramic or PTFE balls and either Viton, EPDM or PTFE seals and O-rings.  Designed to IP65 specification, the AT2-AM is suitable for mounting outside.

The AT2-AM is available as the following model types:-

  • AT2-AM-12-03 for an output flow rate of 3.0 Litres / Hour at 12 Bar pressure
  • AT2-AM-10-04 for an output flow rate of 4.0 Litres / Hour at 10 Bar pressure
  • AT2-AM-08-05 for an output flow rate of 5.0 Litres / Hour at 8 Bar pressure
  • AT2-AM-02-08 for an output flow rate of 8.0 Litres / Hour at 2 Bar pressure

As the AT2-AM pumps are powered from a switch mode power supply which accepts a mains supply of 100 - 240 VAC at 50Hz / 60Hz, making the AT2-AM suitable for export markets.

As part of our Red Dosing Pump range, the AT2-AM is rated hot for continuous dosing duty, and the pump is designed to provide a long trouble free life of accurate chemical dosing.

AT2-AM Specifications

  • Specifications


    High Pressure Proportional Control Dosing Pump

    Model Number:- AT1-AM

    Control Options:-

    • Constant Dosing With Manually Adjustable Output
    • Proportional to 4-20mA input signal
    • Proportional to pulsed input with multiply / divide function

    Control Inputs:-

    • Remote Start / Stop from Volt Free Contact (low level input)
    • Remote Stop from pulse verification input (flow sensor required)

    Control Outputs:-

    • Volt Free Alarm relay output from low level or flow verification inputs

    Frequency:- Max 120 Strokes / Min

    Liquid End Materials:- PVC or PVDF

    Diaphragm Materials:- PTFE

    Valve Housings:- PVC & Ceramic, PVDF & Ceramic, PVDF & PTFE

    Seals & O-Rings:- Either Viton, EPDM or PTFE

    Input / Output Connections:- 4 x 6 / 7mm tubing


    • AT1-AM-20-015:- 0 - 1.5 Litres / Hour at 20 Bar Pressure
    • AT1-AM-18-02:- 0 - 2.0 Litres / Hour at 18 Bar Pressure

    Power Consumption:- 15 Watts

    Pump Body:- Designed to meet IP65

    Mains Supply:- 100 - 240 VAC 50Hz / 60Hz

    Supplied with:- 

    • Surface Mounting Bracket
    • Injection Valve
    • Foot-valve & Strainer Assembly
    • Discharge tubing
    • Suction tubing / Bleed tubing
    • Optional foot mounting bracket
  • Ordering Information


    Model Number*Output (L / Hr)Pressure (Bar)Liquid EndSeals & O-rings
    AT1-AM-20-015-PVC-V 0 - 1.5 20.0 PVC Viton
    AT1-AM-18-02-PVC-V 0 - 2.0 18.0 PVC Viton
    AT1-AM-20-015-PVC-E 0 - 1.5 20.0 PVC EPDM
    AT1-AM-18-02-PVC-E 0 - 2.0 18.0 PVC EPDM
    AT1-AM-20-015-PVDF-V 0 - 1.5 20.0 PVDF Viton
    AT1-AM-18-02-PVDF-V 0 - 2.0 18.0 PVDF Viton
    AT1-AM-20-015-PVDF-E 0 - 1.5 20.0 PVDF EPDM
    AT1-AM-18-02-PVDF-E 0 - 2.0 18.0 PVDF EPDM

    Viton (© DuPont / Chemours)

    For PTFE options please call.


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