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SE 503N-NVPN

Manual

Instructions for Use for the SE 503 Series pH Sensors

1

Sensor connector: VP

2

19 mm A/F, serial number

3

PG 13.5 thread

4

PVDF compression ring 

5

EPDM-FDA O-ring (11.5 x 2.6 mm)

6

Rating plate

7

Junction

8

pH glass, temp detector

!

WARNING – Failure to observe this warn-

ing may result in serious injury.

 The warning symbol on the rating plate 

means:

Read these instructions for use, observe the Spec-

ifications, and follow the Safety Instructions. 

1  Safety Instructions

Please take extra care during installation/fitting of 

the sensor to ensure that neither the plastic body nor 

the thread (PG 13.5) suffer any damage.

2  Intended Use

The Knick SE 503 is a low-maintenance pH sensor with 

a sturdy plastic body and an integrated temperature 

detector. It is provided with a gel electrolyte reference 

system with 2 ceramic junctions.

The sensor is designed for simultaneous measure-

ment of pH and temperature in water and wastewater 

processes. It can also be used at low temperatures.

3  Installation and Commissioning

 •

On unpacking, check the sensor for mechanical 

damage. Report any damage to your Knick service 

team.

 •

Remove the watering cap. Briefly rinse the sensor 

with pure water. After rinsing, the sensor should 

only be dabbed dry with a tissue. Do not rub the 

pH-sensitive glass, since this can lead to electrostat-

ic charging and sluggish response times.

 •

Check the space behind the pH-sensitive glass for 

the presence of any air bubbles and remove them 

by gently shaking the sensor up and down.

 •

Install the sensor in the fitting as described in the 

user manual of the respective fitting.

 •

Connect sensor and cable.

4  Operation

4.1 Calibrating the Sensor

2-point pH calibration is recommended for the SE 503 

sensor. First remove the watering cap. Then dip the 

sensor successively into two different buffer solutions 

with given pH values (e.g., CaliMat pH 7.00 and pH 

4.00) and calibrate the sensor to these buffer values. 

Please refer to the user manual of the pH transmitter 

for further details. 

4.2 Temperature Detector 

The integrated temperature detector is intended for 

automatic compensation of the pH signal and not for 

any high-precision and safe temperature indication 

or control of the process temperature. 

5  Maintenance and Cleaning

Carefully rinse the sensor tip and junction with pure 

water after each operating cycle. Under no circum-

stances must measuring solution be allowed to dry 

on these parts! 

The electrolyte is not refillable. Never keep or store 

the sensor dry!  You should store the sensor with fitted 

watering cap containing ZU 0960 electrolyte (3 mol/l 

KCl).

Contaminants can be removed as follows:
Protein:

Solution of pepsin / HCl

Lime:

Dilute acids

Silver sulfide:

Solution of thiourea / HCl

Grease:

Tenside solution / lye

6  Specifications

Model Code

The markings on each sensor or on the packaging 

label include the following information:

SE 503N/ 1 - NVPN 

Model designation 

  

Sensor connector 

   

VP: VarioPin

  

Solution ground

  

N: Without

  

Length 

   

1: 120 mm

  

Ex approval

   

N: Non-Ex

Further Data
pH range

0 ... 14 

Temperature

-5 ... 80 °C

Pressure, relative

0 ... 2 bar

Junction

Ceramic (2x)

Electrolyte

Gel electrolyte

Reference system

Ag/AgCl

pH sensor material

Glass

Low impedance, low- 

temperature applications

Body material

PSU (polysulfone)

Mounting

PG 13.5

Temp detector

Pt1000

7  Disposal

Observe the applicable local or national regulations 

for disposal.

120 mm

7

1

6

3

4
5

Ø 12 mm

2

091053

TA-SE503N-NVPN-KNX01  20160606

Knick Elektronische Messgeräte  

GmbH & Co. KG 

Beuckestraße 22

14163 Berlin

Germany

Phone:   +49 30 80191-0

Fax:  

+49 30 80191-200

Email:   [email protected]

Internet: www.knick.de

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