The Necessity of Portable Ultrasonic Liquid Level Indicators – A Comment from Coltraco Ultrasonics

On Sunday the 12th of November 2021 the Tokyo MOU Secretariat published a Note of Attention for its Port State Control Officers (PSCOs). The Tokyo MOU is one of the most active regional port state control (PSC) organisations in the world, consisting of 21 member Authorities in the Asia-Pacific Region. This Note of Attention states that:

  1. 3.1 – “When inspecting a fixed carbon dioxide fire-extinguishing system, the PSCOs should be aware that an accident to the system could lead to serious consequences and should follow strict safety precautions to prevent personnel from being put at risk by accident.”
  2. 3.1 – “The principle, structure and operation process of the fixed carbon dioxide fire-extinguishing system installed onboard are not the same. Regardless of relevant inspection experience, the PSCO should not touch the operating arrangements of the CO2 system nor should the PSCO instruct the crew as to how the system operates. The PSCO should ask the crew to explain how the system operates to demonstrate they understand the operation of the system.”

And crucially:

  1. 4.2.1.2 j) – “The PSCO should consider inspecting the following: Check whether the means provided for the crew to safely check the quantity of the fire-extinguishing medium in the containers on board.”

This is a critical development which emphasises the importance of compliance with the IMO SOLAS FSS Code Chapter 5 Fixed gas fire extinguishing systems that clearly states:

  1. 2.1.1.3 – “Means shall be provided for the crew to safely check the quantity of the fire extinguishing medium in the containers. It shall not be necessary to move the containers completely from their fixing positions for this purpose.”

MSC.1/Circ.1318 states that Monthly Testing and Inspections of Fixed Carbon Dioxide Systems are required to be conducted by the ship between external services.

Fixed fire suppression systems are pressurised systems. Therefore, it is reasonable to assume that these systems will leak over time. The only way to determine a cylinder is free from leakage and within the proper range to deliver its design concentration is to check its contents. This is common sense, good practice, and mandated by the IMO SOLAS FSS Code. 

For good reason, the crew is not qualified or certified to dismantle, weigh and re-install CO2 cylinders which are highly pressurised, in a dynamic state, and have an extremely narrow safety margin. In addition, most Marine Servicing Companies only have 4 hours on a vessel in port to test up to 600 CO2 cylinders per ship. It takes 15 minutes in a 2-person team to shut down, dismantle, and weigh a single CO2 cylinder, which is equal to just 16 cylinders in 4 hours. Yet, despite this, every CO2 cylinder on the vessel receives a ‘tested and certified’ sticker and the marine CO2 system is certified, and a certificate is issued.

As the “ship sails alone”, it must act as its own emergency fire service. The crew is justifiably unqualified to perform the dangerous and unsafe process of weighing the CO2 cylinders. However, it is reasonably justified that the IMO SOLAS FSS Code and Tokyo MOU’s Note of Attention calls for every vessel to have the means for the crew to safely check the quantity of the fire extinguishing medium in the containers because they recognise the direct dangers of CO2 leakage to the lives and safety of the crew.

Ultrasonic liquid level indicators are the safest, most efficient way for the crew to check the quantity of the fire-extinguishing medium in the containers without having to operate, dismantle, or move the containers. Therefore, the best way to comply with the Tokyo MOU’s Note of Attention and the IMO SOLAS FSS Code Chapter 5 Fixed gas fire extinguishing systems is by mandating that the crew must have access to a portable ultrasonic liquid level indicator to be able to check the contents of its CO2 cylinders monthly or weekly between the periods of minimum recommended maintenance by MSC.1/Circ.1318.

Yet, due to misunderstanding regarding the application of a part of the IMO SOLAS FSS Code; the need for the crew to have means to safely check the quantity of the fire-extinguishing medium in the containers, many crews still do not have access to ultrasonic liquid level indicators. It is for this reason that the Tokyo MOU’s Note of Attention is significant to shipping. Shipping companies must ensure that their crews have access to portable ultrasonic liquid level indicators onboard.

There could not be a better time for Marine Surveyors from Classification Societies and Port State Controls to ensure the implementation of the IMO SOLAS FSS Code and for Flag States to ensure shipping companies add text within their International Ship Management Code to include the crew requirement to check contents monthly or weekly with a portable ultrasonic liquid level indicator.