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Hanna Instruments UK PCA320 Free & Total Chlorine, pH and Temperature Analyser


The PCA 320 series of analyzers check pH and chlorine levels in applications such as pools and spas, drinking water and influent and effluent discharge of water to ensure public safety, prevent waste and protect the environment by reducing over dosage.

Monitors/controls Free & total chlorine, pH & °C

£2,480.20 (exc.VAT)
£2,976.24 (tax incl.)
Order now for 2 weeks delivery
Full Description Specification

Chlorine, pH, ORP and Temperature analysers

The PCA family are process analysers for the continuous measurement of chlorine and temperature. Also, pH (PCA320, PCA330, PCA340) and ORP where specified. The analysers feature built in data logging, RS 485 digital output, dosing relays, and alarm relays packaged in a wall mount Nema 4 x enclosure. The PCA340 also features two analog outputs.

The PCA300 family uses DPD Colorimetric method in which N, N-Diethyl-p-phenylenediamine indicator and a buffer are mixed together with the sample. The resulting chemical reaction causes a magenta colour to form in the presence of chlorine. The colour intensity is proportional to the concentration. The colour intensity is measured photometrically (light source at a specific wavelength and a photodetector) and converted to chlorine concentration, in mg/L, which is displayed on the front panel. The sampling interval for chlorine measurement is adjustable from 3 to 90 minutes.

The analysers have a dosing relay for the addition of chlorine by a dosing pump or chlorine generator when a reading is below the programmable set point. The technology used by this family for chlorine measurement is the same as that found in portable and benchtop colorimeters providing for consistent results when performing process verification with one of those types of meters.

The PCA320, 330 and 340 also utilise the HI-1005 amplified pH electrode with a built in pt100 temperature sensor and matching pin to measure both pH and temperature. The built in amplifier and matching pin provide for exceptional performance against any electrical noise generated by pumps and motors. These analysers have a programmable dosing relay for the adjustment of pH. The dosing relay can be activated by either on/off or proportional control.

The PCA340 features two selectable 0.20 or 4-20 mA signal output that are scalable for the transmission of readings to external recording devices. The analog outputs can also be set for dosing and used with dosing pumps that accept a 4-20mA analog input. The analog outputs can be used for any of the three measured parameters.

Through the system setup menu, users have the ability to enable or disable the low and high level of alarms for all parameters. The PCA family also offers overdosing protection that generates an alarm if something within the system is not working properly. The system will stop processes until the user corrects the error.

Backlit LCD Display

The PCA family has a backlit display that is easy to read from a distance and allows for up to three parameters to be displayed at a time.

Nema 4x protection

The analysers are enclosed in waterproof casing for superior protection against the elements. The front door of the case has a window for the measurement display while also shielding the DPD reagents from UV light to prevent premature degradation.

DPD Chlorine Measurement Method

The DPD colorimetric method is one of the most common and reliable methods to measure chlorine. The PCA family can use either free or total chlorine reagents and allow for 16,000 measurements to be performed.

Reagent Reminder

The PCA family has a reagent reminder feature to alert the user when the reagents are running low. When the reagents are changed, the counter is reset and the meter automatically tracks the number of readings performed.

Colorimeter Diagnostics

Advanced diagnostics allow for easy troubleshooting of the colorimeter. In the setup menu it is possible to select an option that allows the user to determine the difference between a dark read (LED off) and blank read (LED on). These analysers also automatically perform this check in order to determine when to alert the user that the sample cell needs to be cleaned.

Amplified pH/Temperature, probe (PCA320, PCA330 and PCA340)

An integrated pt100 temperature sensor allows for automatic temperature compensation of pH measurements and allows for monitoring temperature as well. The built in amplifier and matching pin provides for exceptional performance where other probes fail when placed in line with pumps and motors.

Data logging

The analysers can store up to 3500 readings (at least 7 days worth of records when set to a 3 minute sampling interval) that can be reviewed or downloaded to a Windows compatible PC using the HI-92500 software and the RS485 serial port. Logged records contain the date, time and reading of all parameters measured along with any alarm status.

GLP Data

The GLP data allows for the user to review the data and time for the last chlorine and pH calibration.

Digital RS485 output

The analysers have a RS485 digital output that allows for connection to a Windows compatible PC running the HI-925000 software. The software allows for remote monitoring, review of logged data, events and errors, and executing setup options.

Warning messages

Error messages are displayed when the reagents are expired or low and if the colorimeter cell needs to be cleaned.

Two analog outputs (PCA340)

The PCA340 features two selectable 0-20 or 4-20 mA signal output that are scalable for the transmission of readings to external recording devices. The analog outputs can also be set for dosing and used with dosing pumps that accept a 4-20 mA analog input. The analog outputs can be used for any of the three measured parameters.

Two dosing relays

The dosing relays of the analysers can be connected to a pH and/or chlorine dosing pumps. The chlorine relays are proportionally controlled, while the pH relay can be set for on/off or proportional control. The proportional control offers very fine control of doing to prevent any overshoot and wastage of chemicals.

Alarm relay

One SPDT alarm relay is provided that can be activated by adjustable upper and lower chlorine, pH and temperature limits.

Error relay

One SPDT error relay is provided and is activated when an error is present, including a problem with the colorimeter - such as when the reagent counter has reached zero, or when a reading is outside the range for a measured parameter.

Key features

  • Backlit LCD Display
  • Nema 4x protection
  • DPD Chlorine measurement method
  • Colorimeter diagnostics
  • Reagent reminder
  • Amplified pH/temperature probe
  • Data logging of up to 3500 measurements
  • GLP data for review of calibration information
  • Digital RS485 output
  • Two analog outputs for recording or dosing devices (PCA340)
  • Two dosing relays
  • SPDT alarm relay
  • SPDT system error relay
  • Warning messages
  • Each PCA 300 series model is supplied with reagent bottles (2), reagent caps (2), 1 DPD compound powder, tubing and instructions

Swimming pools and chlorine for disinfection

Swimming pool treatment, disinfection or sanitising basically means to rid the pool of bather contamination, destroy bacteria, and control nuisance organisms like algae, which may occur in the pool, filtration equipment, and piping. Of the many techniques used - chlorine, bromine and iodine dosing systems - chlorine is the most common.

About chlorine

Chlorine is a strong oxidising agent that destroys mostly organic pollutants and bacteria and can combine with nitrogen containing compounds, forming chloramines. When dosing chlorine for disinfection, only a portion of the dosed chlorine remains active to actually continue the disinfection process.

When free chlorine combines with a nitrogen containing compound, it becomes a less efficient disinfectant called chloramines. The addition of these two parts gives total chlorine. The target is to keep free and total chlorine equal, and to maintain the combined chlorine concentration (chloramines) near zero. The presence of chloramines is not desired because of the distinctive ‘swimming pool’ smell caused by combined chlorines like di-chloramines. Beside this unpleasant odour, chloramines can irritate the eyes and the mucous membranes.

. . . . More about chlorine

Commercial chlorine for disinfection may be available as a gas (Cl2), a liquid like sodium hypochlorite or bleach (NaOCl), or in a solid state like calcium hypochlorite, chloro-hydantoins or chloro-cyanuric acid compounds. These compounds, once dissolved in water, do establish equilibrium between the hypochlorous acid (HOCl) and the hypochlorite ions (OCl-). Although both forms are considered free chlorine, it is the hypochlorous acid that provides the strongest disinfecting and oxidising characteristics of chlorine solutions.

The amount of hypochlorous acid in chlorinated water depends on the pH value of the solution. Changes in pH value will affect the HOCl equilibrium in relation to the hydrogen and hypochlorite ion. HOCl decreases and OCl- increases as pH increases. At a low pH, almost all the free chlorine is in the molecular form HOCl and at a pH of around 7.5, the ratio between HOCl and OCl- is 50:50.

Since the ionic form OCl- is a slow acting sanitiser while the molecular HOCl is a fast acting, it is important to regularly measure the pH. As a general rule, a pH of about 7.2 is recommended to maintain fast acting disinfection conditions.

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Range0.00 to 5.00 mg/L (ppm)
Resolution0.01 mg/L (ppm)
Accuracy±8% or ±0.05 mg/L whichever is greater
pHPCA320, PCA330 & PCA340 only
Range0.00 to 14.00pH
ORPPCA330 only
Range0 to 2000 mV
Resolution1 mV
Accuracy±1 mV
Range5°C to 75.0°C
ANALOGUE OUTPUT – PCA340 only(2) 4-20mA, 0-20mA for recorder or dosing


Chlorine Calibrationone-point process calibration
Chlorine Sampling RateAdjustable from 3 to 90 minutes
Chlorine Dosageproportional
Chlorine DeltaSelectable from 0.1 to 5 mg/L (ppm)
pH CalibrationAutomatic one or two points; one point process calibration
pH Sampling RateAdjustable from 3 to 120 seconds
pH DosingON/OFF or proportional, relay or 4-20mA output
pH DeltaSelectable from 0.1 to 2pH (hysteresis adjustable from 0.05 to 2pH
Recorder output – PCA310, PCA320 & PCA3304-20mA, 0-20mA
PC ConnectivityRS485 port, galvanically isolated
Baud Rate1200, 2400, 4800, 9600 bps
Data loggingup to 3500 data points
Alarm relaySPDT contact with 5A, 230V resistive load
Dosing relaySPDT contact with 5A, 230V resistive load
System errorSPDT contact with 5A, 230V resistive load
Inlet pressure0.07 to 4 bar with no external pressure regulator (for pressure exceeding four bar an external pressure regulator is required)
Sample flow100 to 300 mL/min
Sample temperature5 to 40°C
Sample inlet/outlet connection12mm male NPT fitting
Drain connection10mm barb
Power supply230 VAC ±10%
EnclosureNEMA-4X Standard, moulded fiberglass polyester with transparent Lexan window
Dimensions/weight318 x 267 x 159mm/5kg without reagents
PCA310Free and total chlorine analyser/controller (230V)
PCA320Free and total chlorine analyser/control, pH control, temperature (230V)
PCA330Free and total chlorine analyser/control, pH control, ORP monitoring, temperature (230V)
PCA340Free and total chlorine analyser/control, pH control, temperature with dual analogue outputs (230V)
HI-70473PCA tubing kit, pressure regulator to drain (2). Each kit includes: transparent Tygon tubes 86L x 3.2ID mm (Length x Internal Diameter) and 105 x 9.5 mm
HI-70474PCA peristaltic pump tubing kit (6). Each kit includes: non- transparent C-flex tubes 55L x 0.8ID mm
HI-70475PCA peristaltic pump tubing kit (2). Each kit includes: non- transparent C-flex tubes 55L x 0.8ID mm
HI-70476PCA reagent bottle tubing kit (6). Each kit includes: non- transparent C-flex tubes 155L x 0.8ID mm
HI-70478PCA tubing kit, bottle to pump (6 ). Each kit includes: non- transparent C-flex tube 150L x 0.8ID mm
HI-70479PCA tubing kit, pump to Y strainer (6 pcs). Each kit includes: non-transparent C-flex tube 150L x 0.8ID mm
HI-70482PCA filters. The kit includes 0.5 µm and 50 µm filters
HI-70496Replacement filter, 0.5 µm
HI-70497Replacement filter, 50 µm
HI-70484PCA complete tubing kit. The kit includes: non-transparent C-flex tubes 150L x 0.8ID (4 pcs), non-transparent C-flex tubes 55L x 0.8ID (2 pcs), non-transparent C-flex tubes 50L x 0.8ID and Y strainer
HI-70485PCA stirrer motor
HI-70486PCA Stirring bar
HI-704871Measuring cell
HI-70488Electrovalve 24VAC/60Hz
HI-70489Electrovalve 24VAC/50Hz
HI-70492Electrode holder (PCA330)
HI-70493Closing cap for electrode holder
HI-1005Amplified pH electrode with matching pin and Pt100 (PCA320/330 only)
HI-2008Amplified ORP electrode with Matching Pin (PCA 330 only)
HI-70481Total Chlorine Reagent set for PCA buffer citrate, 500ml
HI-70430Free chlorine reagents set for PCA (the most stable), recommended for long term measurements, 500 mL (2) + 6 g powder
HI-70480Free chlorine reagents set for PCA, recommended for short term measurements, 500 mL (2) + 5 sachets (DPD)
HI-70490Free chlorine reagents set for PCA, 500 mL (2) + 5 sachets (DPD)
HI-70452DPD reagent, 5 sachets
HI-70460Total chlorine indicator solution for PCA, 500ml – (After addition of 5 powder sachets (HI-70452-0))
HI-70461Total chlorine buffer solution for PCA, 500ml
HI-70450Free chlorine indicator solution for PCA, 500ml – (After addition of 5 powder sachets (HI-70452-0))
HI-70451Free chlorine buffer solution for PCA, 500ml
HI-7004LpH 4.01 buffer solution, 500ml
HI-7006LpH 6.86 buffer solution, 500ml
HI-7007LpH 7.01 buffer solution, 500ml
HI-7009LpH 9.18 buffer solution, 500ml
HI-7010LpH 10.01 buffer solution, 500ml
HI-7020L200-275mV buffer solution, 500ml
HI-7091LPretreatment reducing solution, 500ml
HI-7092LPretreatment oxidizing solution, 500ml
HI-70300LStorage solution, 500ml
HI-70823.5M KCL electrolyte, 30ml
HI-7061LElectrode cleaning solution, 500ml
HI-92500Windows® compatible software