PAH500 Frequently Asked Questions


Dokument-ID TE12377


Veröffentlichungsdatum 05.01.2022
PAH500 Frequently Asked Questions

FAQ's: PAH500

Q: What parameters are required to be monitored on the inlet and outlet of EGCS for Maritime?
A: PAH, pH, turbidity and conductivity (optional): ~pH 6.5 +/- 2, PAH <50 ppb, Turbidity <25 NTU/FNU

Q: Where is the PAH500 used?
A: The PAH500 is used only in Maritime applications.  Specifically, it is used on the inlet and outlet of exhaust gas cleaning systems or EGCS (scrubbers) being utilized on vessels.

Q: What type of scrubber systems are there?
A: Open loop, closed loop, and hybrid loop systems.  Open loop is most common currently due to lower initial and operating costs.

Q: Can the PAH500 be used in land-based municipal and industrial applications?
A: No.  The PAH500 is for Maritime only, specifically the exhaust gas cleaning systems.

Q: Can a gateway sensor be replaced individually?
A: No, the gateway and probe are a matched pair.  Matching serial numbers are on each component of the sensor setup.  So the entire probe and gateway setup must be replaced or sent back for repair.

Q: Can I connect the PAH500 to an SC200 with an internal gateway?
A: No, there are several data inputs programmed in a gateway to match it to the PAH500 in order for the correct values to be displayed.

Q: What controllers can be used with the PAH500 in Maritime applications?
A: Currently only the SC1000 controller is certified to be used in the Maritime appication as it is type-approved by the DNV-GL.

Q: What is the best way to mount the PAH500?
A: The PAH500 uses flow through cell sampling.  Preferred mounting is vertical with the cable connection on top, which allows for easy cleaning and calibration.  If needed, the probe can be installed up to 75° from horizontal.  Sample should be flowing upwards to avoid bubble interference during measurement.

Q: What can be used to clean the PAH500?
A: Note: the customer should not use any detergents containing ingredients such as lanolin or any other hand-softening ingredients as this will coat the optics and cause inaccurate readings. 
The quartz tube cleaning should be done with a soft brush or the provided foam swabs (preferred) from Hach.  Absolutely no cotton swabs.  Cleaning surfactancs, such as Alconox® or Liqui-Nox® can be used or any surfactant that is non-lanolin (hand-softening) based.  If cell is not completely contaminant free, an isopropyl greater than 90% and/or 5.25N sulfuric acid can be used to remove remaining contaminants.

Q: Is calibration during the commissioning period necessary?
A: Not necessary but recommended, and you only need to perform a 1-point clibration with the zero standard (DI water).

Q: What standards should be used when performing a calibration?
A: Calibration is performed at 0 ppb using DI water, and 50 ppb.  The 25 ppb is for a check, which can be used after calibration or whenever the customer is concerned that the reading may be inaccurate.  These standards are available through Hach.

Q: How often should the PAH500 be calibrated?
A: The PAH500 should be calibrated at least on an annual basis, and factory inspected and calibrated after two years.  It is recommended that periodic calibration checks are done by the user to ensure that the PAH500 is reading correctly.

Q: When going into the calibration process, what should we set the sensor status to?
A: Selecting the "Hold" option is best practice, as this avoids sending a false alarm when using the 50 ppb standard via the 4-20 relay.  However, it is recommended that the vessel protocol is followed in all cases.

Q: How do we confirm that a cleaning is needed or if the cleaning process was thorough enough?
A: The SC1000 can display the raw mV signal from the sensor.  Printed on the probe, there is a slope value and offset value in mV; if the raw displayed mV values are well below the stated values, this would confirm that the sensor is stil in need of further cleaning.

Q: Do you have recommended spare parts for customer daily maintenance?
A: It is recommended to have Liqui-Nox or Alconox and isopropyl alcohol for cleaning, foam swabs, and a calibration kit.  Optionally 5.25N sulfuric acid can also be used for cleaning if there is excessive contamination.  Part numbers can be found in the data sheet and user manual.

Q: What regulations need to be known for use of Hach equipment in exhaust gas cleaning systems?
A: Please visit for more information

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