FOM-7.3	Fleet Operations Manual FOM Calibration of Measuring Instruments	Doc No.: FOM 7.3 Revision: 01 Date: 15 Oct 2024 Issued by: DPA Approved by: MD

1 Calibration Procedures

• Calibrate instruments mentioned in this document as per maker’s instructions.
• In addition to the annual shore calibration; the fixed gas detection systems are to be calibrated as per requirements outlined in section 4 below.
• Use certified equipment, samples or test specimens.
• Use maker’s recognised agents or Service Company if certified equipment is not onboard.
• Identify each instrument with a unique number and indicate the last calibration date on the instrument.
• Enter these details in a specific Equipment Calibration Record, CCR13, for each piece of equipment.

2 Instruments

3 Bilge Oily Water Separator

a) For tankers – Annually

b) For bulk carriers - Each dry docking

Bilge oily water separator requirements:

• A 'calibration certificate' must be issued by the manufacturer specifying each unit, type and serial number and retained by Master with the trading certificates.
• As far as possible, the oil sensor makers’ approved agents should be used for carrying out the calibration.
• If this is not practical, then any of the automation service companies listed in the approved vendors list can be utilized for this job.
• The procedure generally requires the sensor to be removed from the separator and sent to the workshop where a pre-measured sample is used for calibration.
• After the calibration, a certificate noting the make/serial number of the equipment, test result and date of the calibration must be obtained from the testing company.
• The original of this certificate must be kept onboard with a copy in office certificate folder /e-file of the vessel.

4 Gas Detection Instruments

4.1 General Requirements

Gas detection instruments require special attention as the equipment is often scrutinized by Port State and Vetting Inspectors. It is extremely important that deck officers know and can demonstrate the basic procedures for onboard calibration.

4.1.1 Fixed Hydrocarbon Gas Detection Equipment

It should comply with requirements of MSC1/1370. With regards to Maintenance, below should be complied with:

The following onboard maintenance should be carried out monthly and after any fault condition:

1. Visual inspection;
2. Testing of audible and visual alarms; and
3. Zero and span calibrations as described below

Calibration

The system should be designed to permit onboard calibration by the crew.

Calibration of the detector should be performed with a zero-calibration gas and a span calibration gas. The span calibration gas should be:

• Methane, for systems intended for sensing methane and hydrocarbon mixtures containing methane;
• Propane for systems intended for sensing hydrocarbon mixtures not containing methane; or
• The actual gas or a chemically similar gas with a comparable flammable range.

The concentration of the span gas used for calibration should be equal to the alarm setpoint or as determined by the Administration.

As mentioned in section 1) Calibration procedures, fixed gas detection system shall be annually calibrated and checked for operation by authorised shore personnel.

4.1.2 Portable/Personal Gas Detection Equipment

• All portable and personal gas monitoring equipment must be serviced and calibrated as per manufacturer’s instructions and at manufacturer’s recommended intervals. Manufacturer’s letter to this effect should be kept available for good order sake, along with calibration and maintenance records.
• For Riken Keiki instruments onboard the vessel, they can be calibrated onboard every month or earlier if required by manufacturer’s manual or suspected for any error.
• Each personal and portable gas meter shall be tested for proper operation and alarm prior use.
• Refer to the manufacturers instruction manuals when preparing to calibrate a specific instrument.
• Each vessel must have a full set of English language instruction manuals for each type of Gas Detection Instrument carried.
• All vessels must maintain an inventory of Gas Detection Instruments and accessories for the vessel type as specified on:
  • FOM 10.6 Gas detection instrument (Crude / Asphalt / MR Tankers)
  • FOM 10.8 Gas detection instrument (Chemical Tankers)
  • FOM 10.9 Gas detection instrument (Gas Tankers)
• Test Gas Detection instruments prior each use.

4.2 Combustible Gas Indicator

Generally, to calibrate a combustible gas indicator (CGI):

• Inflate a test bag (a balloon like device with a hose and hose crimping clamp) with a known concentration of span gas and connect the hose to inlet side of the CGI
  • Release the clamp and induce the fuel/air concentration of span gas, usually 50% LEL, and verify the instrument reads the same concentration as the gas induced.
  • If a 50% reading or within the range as specified on the span gas is achieved on a 0-100% scale when 50% LEL gas is used, the meter is in calibration.
  • If not, the span adjustment screw must be rotated until the meter reads 50% while gas is induced. If the crew is in doubt, the meter must be landed for servicing.

4.3 Tank-scope

Tank-scopes are required on tankers to measure the percent volume of hydrocarbon in an inert cargo tank. Generally, to calibrate a Tank-Scope:

• Inflate a test bag with a known concentration of span gas and connect the hose to inlet side of the Tank-Scope
  • Release the clamp and induce the Hydrocarbon/inert gas mixture span gas, usually 8%.
  • Hydrocarbons mixed by volume in an inert gas, such as Carbon Dioxide, and verify the instrument reads the same concentration as the gas induced.
  • If an 8% reading or within the range as specified on the span gas is achieved on a 0-100% scale when an 8% Hydrocarbon gas mixture is induced, the meter is in calibration.
  • If not, the span adjustment screw must be rotated until the meter reads 8% while gas is induced. If the crew is in doubt, the meter must be landed for servicing.

4.4 Oxygen Meters

Oxygen meters are instruments that detect the percentage of oxygen in the atmosphere. To calibrate an Oxygen Meter:

• Turn the unit power on, allow to warm-up, and a reading of 21% should be obtained in normal outside air
  • If the meter reads 21% in normal air, the meter is in calibration. If not, the span adjustment screw must be rotated until the meter reads 21% while in normal air
  • Oxygen meters used to check oxygen levels in an inert atmosphere should be zeroed with 99.9% Nitrogen. A test bag is inflated and connected to the inlet of the meter, if a zero reading is achieved, the Oxygen sensor is good.
  • If not, the sensor will need to be replaced. If the crew is in doubt, the meter must be landed for servicing.

4.5 Multi-gas Color-metric Detector Tubes and Pumps

Multi-gas tube type detectors are used to measure specific quantities of known airborne toxins. The Drager bellows pump and detector tubes are the company standard. To Calibrate a Drager type instrument:

• Perform a leak test of the bellows by squeezing the bellows fully closed and inserting an un-opened tube
  • If the instrument does not expand within the time specified in the user manual, the instrument is in calibration.
  • Refer to the instructions provided in the tube box to determine the number of strokes required.

5 Failure of Equipment

In case any portable gas detection instrument or fixed gas detection system fails, the company is to be informed and a Risk Assessment is to be carried out.

5.1 In Port

In case the vessel is calling a port without an operational portable gas monitoring instrument, control measures should include obtaining an operational instrument in the port before port operations commence.

5.2 At Sea

In case a portable gas instrument fails at sea, equipment redundancy will ensure atmosphere monitoring can be maintained.

In case both instruments fail, shipboard operations are restricted as follows.

Equipment	Operational Restrictions
Combustible Gas Detector	No enclosed space entry, No tank cleaning, No tank purging, No tank gas freeing, No hot work outside engine room workshop
Tank Scope	No tank cleaning, No tank purging, No tank gas freeing
Oxygen Meter	No enclosed space entry, No tank cleaning, No tank purging, No tank gas freeing

6 Referenced Forms and Checklists

CCR13 – Equipment Calibration Record for Gas Meters

E63 – Equipment Calibration List