BWMS essential guide

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BWMS essential guide

Step 1: Type of validation

Out of the two validation the USCG is considered to be stricter and BWMS with USCG certification were subjected to tougher and more rigorous tests during the validation process.

Step 2: Validation version

Make sure this is the validation type presented to you. Any other validation name, even if it has the word New in it, is not the latest and most up to date.

Step 3: Envelope of operation

This is strictly defined in the certification and the wider the envelope of operation,
the less constraints on the vessel's operation in relation to ballasting and deballasting.

Note that for the same system, the IMO envelope of operation and the USCG envelope of operation might be very different, with the USCG having the more constraining envelope of operation. Always request to know both certifications’ envelope of operation.
Flow rates
Make sure the max flow rates are adequate to your vessel.
Water condition
This can be expressed in UV transmittance (UVT) or Intensity. In many cases, this information is not public domain and you must request for it to be included in the technical specifications of the proposal. Systems with lower UVT limits (available down to 40%) and lowest intensity readings are those which provide you with the most flexible operation.
Water type and water temperature
These are additional limiting factors for the envelope of operation, make sure the certification includes all or as many as possible types of water (sea, fresh, brackish) and that water temperature is not a limiting factor (if using electro-chlorination). For example, electro-chlorination BWMS cannot operator in fresh and brackish water. This is a considerable limiting factor on the vessels ballasting and deballasting operation.

Step 4: Operation according to intensity

continouse versus steps
  • Atlantium
  • Conventional 

Step 5: Holding time is always related to water UVT or Intensity

Did you know?

According to the USCG, the minimum holding time for the lowest water conditions of 40% UVT is 24 hours. Lower holding times, down to 2 hours are available in the higher UVT ranges of 96-98%. For the IMO, zero holding time is available and is also related to water UVT. Always inquire about the holding time at the most extreme water conditions as most BWMS are validated for 72 hours holding time at the low UVT / intensity ranges.

Do you need to reduce your holding time?
Download new regulation

Step 6: Electro-chlorination

Parameters to be checked:

  1. Water salinity - the system cannot operate below a certain salinity (fresh and some of the brackish water) . Make sure that you have a contingency plan for such case by preparing ballast tank with sea water or having salt to be added to the water for generating the active substance.
  2. Water temp, pH and other physical chemical parameters – effectivity depends on water temp. and other parameters, make sure the license is covering the expected water condition.
  3. Fresh supply of chemicals - active substance neutralizing agent (SBS, SMBS) needs to be fresh, else will not be effective and you might face chemical discharge violation.
  4. Storage of chemicals – storage of the neutralizing agent according to relevant standards.
  5. Training and certifying –certifying your crew to deal with hazardous materials, make sure they have a valid certification.
  6. Hydrogen evacuation – Hydrogen must be evacuated – explosive gas. The functionality of the evacuation devices must be verified and controlled.
  7. Frequent calibration – of the residual active substance equipment for avoiding chemical discharge violation. The difference in measuring devices is the major issue nowadays associated with violation dispute.

Blending issues:

  1. Mixing water in the tank - the concentration of the active substance depends on the residual water in the tank, therefore make sure it is taken as a parameter in your control system.

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