How to Calibrate the BilgMon 488

Full Guide to Calibration Certificates, Calibration Checks, and Measuring Cell Replacement

Correct calibration is essential for accurate performance of the BilgMon 488 15 ppm bilge alarm. This how-to-guide explains the two calibration-related tasks included in the BilgMon 488 maintenance schedule:

Managing the 5-year calibration certificate supplied with every new sensor unit
Performing a periodic calibration check using the Calibration Check Kit

For related topics, see:

Martin Søvind Jensen

Product Manager

Tel: +45 2761 4502

Email: Martin.Sovind@insatech.com

Write to Martin

1. Understanding Calibration Requirements

The BilgMon 488 has two separate calibration processes, and it is important to distinguish between them.

1.1 The 5-Year Calibration Certificate (Sensor Unit Calibration)

Each BilgMon 488 measuring cell is delivered with a factory calibration certificate valid for 5 years.
When the certificate expires:

The sensor cannot be recalibrated.
You must replace the entire measuring cell.
Replacement takes approximately five minutes and requires no modification of the master unit.
A new sensor unit always comes with a new 5-year calibration certificate.

Why replacement is better than recalibration

If you need calibration of the sensor unit itself, it is cheaper and faster to buy a new measuring cell with a new 5-year calibration certificate.
We can assist you with selecting the correct model:

Black Sensor Unit (Measuring Cell)
Blue Sensor Unit (Measuring Cell)

Order Directly from Insatech

Brannstrom Sensor Unit Black Certificate

2. Regular Calibration Checks

In addition to the 5-year certificate, the BilgMon 488 requires periodic calibration checks. These checks verify that the sensor still measures accurately and has not been impacted by contamination, deposits, or installation issues such as air bubbles.

Calibration checks may be required more frequently depending on vessel procedures, class society requirements, or your internal SMS.

If a calibration check fails, you should first:

Clean the measuring cell thoroughly (see How to Maintain the BilgMon 488)
Check the installation for bubbles or debris
Repeat the calibration check

If the sensor still fails, the measuring cell likely needs to be replaced.

3. The Calibration Check Kit

To perform calibration checks, you need the BilgMon 488 Calibration Check Kit, which contains everything required for the 40 NTU verification test.

Kit contents

Cleaning brush
Syringe
500 ml bottle with lid
50 ml bottle of 40 NTU calibration check liquid
Cleaning cap
Instructions

You can purchase the kit here: BilgMon 488 Calibration Check Kit

Order Directly from Us

4. Step-by-Step Calibration Check Procedure

Step 1: Enter the Calibration Menu

Navigate to the Cleaning & Test menu.
Select the ‘Check 40NTU cal’ submenu.
Press ENTER to begin the test.
Note: The clean water valve does not open during this procedure.

Step 2: Prepare the Sensor

Close the clean water supply.
Drain the measuring cell completely.
Fill the sensor tube with 40 NTU calibration fluid using the syringe or bottle from the kit.

Step 3: Verify the Reading

The display must show a value between 80% and 100%.

If within range, an “OK” message appears above the RETURN button.
Press RETURN to store the updated ‘Cal checked’ date in the Sensor Info menu.

Step 4: Troubleshooting Failed Checks

If the reading is outside the acceptable range:

Clean the measuring cell thoroughly
Verify that no air bubbles or particles are present
Repeat the calibration check

If the test still fails, the measuring cell is likely defective or out of tolerance and should be replaced.

5. When to Replace the Measuring Cell

Replace the measuring cell when:

The 5-year calibration certificate has expired
Repeated calibration checks fail
The sensor tube is contaminated or damaged
The sensor readings are unstable

Replacement is quick and requires no modification to the master unit.
Internal product links to insert:

6. Summary

Calibrating your BilgMon 488 involves two core activities:

Tracking and replacing the 5-year calibration certificate by installing a new measuring cell
Performing regular calibration checks using the Calibration Check Kit

With correct calibration routines, your BilgMon 488 maintains peak accuracy and always ensures compliant 15 ppm monitoring.