Free chlorine
0–20 ppm; 0.001 ppm resolution. The guide states a 0.01 ppm detection limit and 0.04 ppm quantitation limit.
Halogen MP5
Blue self-cleaning, reagentless free-chlorine monitoring for defined water-quality points.
Follow free chlorine with the blue MP5.
MP5 measures free chlorine using a reagentless, three-electrode system. The integrated pH, ORP, conductivity and temperature information helps your team review the water conditions alongside the residual.
Continuous mechanical and electrochemical cleaning keeps the measuring surfaces working, with no membrane or electrolyte replacement. Use D20 for a local display and site outputs, or discuss an appropriate PLC integration.
Cleaning built into the measurement
A small motor drives a magnetically coupled impeller. Its movement circulates water at the sensing end and agitates cleaning beads across the measuring surfaces.
The beads help keep the electrodes and pH element clean while the sensor works. Electrochemical cleaning supports the mechanical action. There are no analysis reagents to replenish and no sensing membrane or electrolyte to replace.
This local movement supports measurement at low bulk-flow velocities. The sensor still needs representative water, a suitable installation and planned reference checks.
Built for demanding water conditions
Iron-rich water can leave heavy deposits on a sensor. Halogen’s continuous self-cleaning helps keep the measuring surfaces working, reducing routine cleaning in challenging conditions.
These photographs show an MP5 after five months in high-iron borehole water, without cleaning, recalibration or other intervention during the published trial.
Discuss your application
MP5 operating envelope
Values from the supplied MP5 product guide. Select the exact sensor variant and mounting arrangement with PMA.
Measurement interval
A nominal 60-second measurement interval. Allow for commissioning, reference checks and site signal handling.
Water chemistry
Chlorine sample pH 6.5–9.0. Published conductivity range 50–10,000 µS. Confirm the water matrix and conductivity basis.
Sample temperature and pressure
1–55°C sample temperature and a published 10 bar pressure limit, subject to the complete installation rating.
Sensor supply
24 V DC ±10%; 50 mA operating consumption with 200 mA maximum startup. Account for cabling and power provision.
Calibration checks
Typical six-month calibration stability. The guide requires checks at least every six months; assess local reference-check needs.
A clean sensor still needs a representative location
At a works, decide whether the reading is intended to describe a particular treated-water outlet, a blend or another process point. At a reservoir, relate it to the inlet, outlet or immersed location.
Choose a flow cell, in-pipe fitting or immersion arrangement that suits the sensor variant. Include isolation, drainage, sample transit time and maintenance access in the site review.
Applications for UK water operators
Practical guidance for choosing the monitoring point and using the resulting trend.
Chlorine residual at treatment works
Follow a defined treated-water point, reference checks and signal quality.
Reservoir chlorine monitoring
Connect residual trends to inlet, outlet and storage operating conditions.
Chloraminated-water monitoring
Keep monochloramine and free-chlorine trends in a clear investigation record.
Downloads for your technical review
Read the manufacturer product guides for installation, operation, calibration and model-specific limits.
MP5 and D20 product guide
The supplied MP5 guide uses the MP5A model designation. PMA presents this model as MP5.
MP6 and D20 product guide
Operating modes, reference calibration, installation requirements and technical specifications.
Your questions, answered
Is accuracy the same in every condition?
No. The guide gives condition-dependent accuracy relative to a calibrated DPD reference, including pH, temperature, conductivity and flow changes. Use its complete specification for your expected water conditions.
Can MP5 measure monochloramine?
MP5 is presented here for free chlorine. For monochloramine and free chlorine in suitable chloraminated water, review MP6 with PMA.
Does reagentless mean maintenance-free?
No. There are no analytical reagents, sensing membrane or electrolyte to replenish, but reference checks, inspection and servicing still need to follow the guide for the supplied model.
How does the sensor clean itself?
A motor-driven impeller circulates water at the sensing end and moves cleaning beads across the measuring surfaces. Electrochemical cleaning supports that mechanical action.
Which installation should I choose?
Review a suitable in-pipe, immersion or flow-cell arrangement with PMA. The sensor variant, water conditions, isolation and service access determine the appropriate mounting accessories.
What should I send PMA?
Send the expected free-chlorine range, pH, conductivity, sample temperature and pressure, monitoring point, power and required outputs. Include site photographs or a process sketch where available.
Looking after your world since 1971
PMA connects the measurement, installation and operating team. We help you review the application, select suitable instrumentation and plan commissioning, training and ongoing service.
Build your system
Start with your water chemistry. Choose the installation and connections, then see how your sensor and controller work together.
Self-cleaning. Reagentless.
Choose a sensor to begin
Find the right fit for your water.
Tell us about your disinfectant, water chemistry and installation. PMA can help you work through the sensor, controller and integration requirements.
Start a conversation.
01484 843 708sales@pma.uk.comBrook Mills House, Carr Lane
Slaithwaite, Huddersfield, HD7 5BG