JUMO 201040 Operating Instructions Manual Download Page 14

14

7.2 Calibrating the ammonia sensor

General information

The slope of the sensors varies somewhat from instance to instance
and  also  changes  during  operation  (caused  by  deposits  such  as
lime, or by wear). This changes the output signal of the sensor. 
The software of JUMO dTRANS pH 02 and JUMO AQUIS 500 pH
transmitters is specifically geared to coolant monitoring. They use a
typical, concentration-dependent characteristic line. The individual
properties  of  the  sensor  are  only  taken  into  account  here  by
offsetting  the  zero  point.    This  considerably  reduces  the  effort
required for calibration.

Ammonia calculation

The ammonia sensor output signal follows a straight characteristic 
line up to voltage U

1

 (default = 84 mV). Above U

1

, the characteristic 

line will be curved (see diagram on Page 9).

Lower detection limit U

0

U

0

 is the voltage supplied by the ammonia sensor in an ammonia-

free process medium. 
The default setting for U

is 138 mV.

One-point calibration

With one-point calibration, voltage U

0

 is determined (in the 

ammonia-free process medium).
Requirement:
The process medium must be free from ammonia.

Immerse the ammonia sensor in the process medium.

Start one-point calibration on the JUMO transmitter.

Wait until the voltage shown on the JUMO transmitter has 
stabilized.
Please do not make any changes by pressing the 

 or 

 

keys!

End calibration by pressing the 

 key.

The JUMO transmitter shows 0.0 ppm.

PGM

Summary of Contents for 201040

Page 1: ...Ammonia sensitive sensor for measuring ammonia in aqueous solutions Type 201040 B 201040 0 Operating instructions V1 00 EN 00451666 ...

Page 2: ......

Page 3: ...endence of the ammonia sensor into account when using it in combination with JUMO dTRANS pH 02 or JUMO AQUIS 500 pH 13 7 2 Calibrating the ammonia sensor 14 8 Maintenance 16 8 1 Refilling replacing the electrolyte 17 8 2 Storing the sensor in the storage container 19 8 3 Removing the electrode from the storage container 19 9 Accessories 20 9 1 Quick change fitting for ammonia sensor 20 9 1 1 Repla...

Page 4: ...contact the nearest subsidiary or the head office in such a case Please read this operating manual before placing the instrument in service Keep the operating manual in a place which is accessible to all users at all times For technical questions Service hotline Phone 49 661 6003 300 or 49 661 6003 653 Fax 49 661 6003 881300 or 49 661 6003 881653 E mail service jumo net More information can be fou...

Page 5: ...m changes the pH value of the electrolyte The NH3 concentration in the process medium can be measured in this manner The electrolyte contains ammonium NH4 ions with which the sample gas is in chemical equilibrium 2 3 Operating conditions The concept of an ammonia leakage monitoring system must ensure that the escaping coolant reaches the ammonia sensitive sensor type 201040 quickly The sensor must...

Page 6: ...7 part no 00379538 JUMO type sheet 202820 JUMO AQUIS 500 pH transmitter controller type 202560 20 888 000 310 000 23 000 part no 00480050 JUMO type sheet 202560 or JUMO dTRANS pH 02 transmitter controller type 202551 01 8 01 4 0 00 23 part no 00560379 JUMO type sheet 202560 Low noise coaxial cable 1 5 m long part no 00085154 JUMO type sheet 202990 or Attention The process medium must not contain a...

Page 7: ...ng length 120 mm Diameter 12 mm Connection Pg 13 5 screw on head Medium pressure Sensor in quick change fitting Part no 00379538 installed 2 to 3 bar max 6 bar Sensor free 1 bar abs atmospheric pressure Suitable transmitter JUMO AQUIS 500 pH or JUMO dTRANS pH 02 Note Use of an impedance converter type 202995 00 91 part no 00300455 JUMO type sheet 202995 is recommended at low temperatures as the el...

Page 8: ...esence of ammonia in the process medium is heavily dependent on its pH value see above diagram In the acidic range there will be a predominance of ammonium NH4 ions that are not detected by the sensor At approx 9 3 pH the concentration ratio of ammonia NH3 and ammonium NH4 is about 1 1 It is only in the heavily alkaline range that ammonia is predominant ...

Page 9: ... value up to higher values The correlation between ammonia concentration NH3 and voltage U is given by the Nernst equation In the ideal case the value of slope S is 58 16 mV decade at 20 C U0 is the cell zero point The dependence levels off as the ammonia concentration falls that is there is a lower detection limit The following diagram shows a typical characteristic line NH H O NH 3 2 4 OH U U S ...

Page 10: ... on both sides of the film 6 As the partial pressure changes so does the pH value in the thin layer of liquid upstream from the glass membrane 5 This process is recorded by the hydrogen ion sensitive glass membrane 5 As the partial pressure depends on the concentration of ammonia in the sample solution the pH value can be used to determine the ammonia concentration in the solution 1 Reference syst...

Page 11: ...ium must be free of particles and dirt It may be necessary for the customer to provide a filter upstream from the quick change fitting Tr 12 9 x P1 5 Pg13 5 ø12 0 5 156 120 12 7 Screw on head Hose connection Electrode shaft PPO silicone Membrane cap stainless steel 1 4571 O ring FPM Gas permeable PTFE film ...

Page 12: ... 2 4 Coolant monitoring page 6 Ammonia sensor connection Internal conductor measurement electrode External conductor reference electrode 7 Startup Attention The sensor 1 must only be removed from or returned to the storage container 3 once the union nut 2 has been completely unscrewed Otherwise the sensor will be destroyed by the buildup of negative or positive pressure The pipelines must be rinse...

Page 13: ...n in order to measure correctly The temperature can either be measured automatically by a temperature probe e g Pt100 Pt1000 or the user must set it manually on the transmitter Fully unscrew the union nut 2 and slide it up Pull the sensor 1 out of the storage container 3 Remove the O ring from the sensor shaft The sensor is now ready to measure Pour the electrolyte away Keep the storage container ...

Page 14: ...a calculation The ammonia sensor output signal follows a straight characteristic line up to voltage U1 default 84 mV Above U1 the characteristic line will be curved see diagram on Page 9 Lower detection limit U0 U0 is the voltage supplied by the ammonia sensor in an ammonia free process medium The default setting for U0 is 138 mV One point calibration With one point calibration voltage U0 is deter...

Page 15: ...15 Note With manual temperature compensation the fixed temperature of the medium assigned by the user is shown on the JUMO transmitter ...

Page 16: ...ing page 22 If the flow rate of the medium is too low in general the porous PTFE washer part no 00583477 white standard can be replaced by the less dense version part no 00583479 black for higher flow rate Section 9 1 1 Replacing the PTFE washer in the quick change fitting page 22 Typically the electrolyte of the gas sensitive sensor must be replaced semi annually or annually depending on the cool...

Page 17: ...Remove the vent wedge 6 In the gap 4 top up the electrolyte to the brim Fill the new membrane cap 2 with three drops of electrolyte to lubricate the O ring in the membrane cap This will prevent the sensitive PTFE membrane 1 from being damaged by the glass membrane 3 Place the membrane cap 2 on the thread and screw it on with a quarter turn Attention Do not screw the membrane cap all the way down a...

Page 18: ...icone tubing Screw the membrane cap 4 all the way down excess electrolyte will escape Remove the vent wedge 3 Use an absorbent cloth to soak up excess electrolyte The ammonia sensor is now ready for startup Attention The electrolyte must not get into the plug type head 1 of the sensor This causes contact problems 2 4 3 1 ...

Page 19: ...ion nut 2 8 3 Removing the electrode from the storage container Fully unscrew the union nut 2 Then take the sensor out of the storage container Attention It is essential to keep to the procedure described below as otherwise pressure buildup will destroy the sensor membrane The sensor must not be stored dry Attention Do not move the sensor in the wet storage container once the screw fitting is clos...

Page 20: ...nsor A Turn the handwheel to close maintenance B Turn the handwheel to open operation 1 Quick change fitting for ammonia sensor PP Part no 00379538 2 Discharge G1 8 A POM hose connection 3 Handwheel 52 ø60 22 5 57 5 ø35 G1 1 4 A 163 Pg13 5 20 35 B A 1 2 3 3 ...

Page 21: ...may only be removed when the fitting is closed Do not close the discharge 4 Optimum operating pressure 2 to 3 bar Maximum operating pressure 6 bar Note If too much process medium runs out of the overflow Reduce the system pressure Mount the quick change fitting in the bypass with a control valve upstream If not enough process medium runs out of the overflow the ammonia sensor may respond too late ...

Page 22: ...monia sensor from the fitting Dismantle the fitting Loosen the three hexagon socket screws 1 do not unscrew them completely Pull the electrode fixture 2 out of the fitting Unscrew the cap 5 on the lower end of the electrode fixture 2 Replace the PTFE washer 4 1 Hexagon socket screws M4 2 Electrode fixture 3 O ring 4 PTFE washer 5 Cap stainless steel wrench size 16 max 3 5 Nm 6 Handwheel 16 1 2 4 5...

Page 23: ...n the fitting Tighten the hexagon socket screws 1 Screw the gas sensitive ammonia sensor into the fitting about 3 Nm Turning the handwheel 5 to the right clockwise closes the fitting and moves the gas sensitive ammonia sensor into the process medium Attention When mounting the PTFE washer 4 make certain the O ring 3 is resting in the groove ...

Page 24: ...shers 00583479 Error Possible cause Action The measured value drifts Pressure temperature fluctuations in the process medium Keep values constant Coolant concentration is too high Use an ammonia sensor with extra code 854 low temperature applications Widely fluctuating measured values Air bubble downstream from the membrane of the ammonia sensitive sensor Refill replace electrolyte No process medi...

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Page 28: ...s 36035 Fulda Germany Phone 49 661 6003 0 Fax 49 661 6003 607 E mail mail jumo net Internet www jumo net JUMO House Temple Bank Riverway Harlow Essex CM20 2DY UK Phone 44 1279 63 55 33 Fax 44 1279 63 52 62 E mail sales jumo co uk Internet www jumo co uk 6733 Myers Road East Syracuse NY 13057 USA Phone 315 437 5866 1 800 554 5866 Fax 315 437 5860 E mail info us jumo net Internet www jumousa com ...

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