Flagship Ultrasonic Liquid Level Indicator Designed for the Marine Environment

The Portalevel® MAX MARINE PLUS is an all-new liquid level indicator designed specifically for use onboard marine vessels and environments within the marine sector. Now with three extended calibration features and a display that will indicate if the sensor is in the GAS or LIQUID phase of a fire suppression cylinder. This portable and battery powered, liquid level indicator is designed to non-invasively, accurately, and reliably measure the level of fire suppression agent contained within a cylinder. The UL-Approved Portalevel® MAX MARINE PLUS is suitable for CO2, most Liquified Clean Agents, and Halons.

P/N: 2290334-MAXMN
NSN: 6680-99-192-2735
IMPA MSG P/N: 652776


Get help buying? Chat now, email or call +44 207 629 8475

Send Pricing & Information


Marine Ultrasonic Liquid Level Indicator

One of the latest additions to the Portalevel® range, the all-new Portalevel® MAX MARINE PLUS offers vast improvement to the functionality and display, all packaged into a smart, ergonomic, and rugged enclosure. With the implementation of three calibration modes, the user has much greater control when testing a large variety of liquids and fire suppression systems. A new user interface upgrade now indicates which phase the sensor is placed, indicating either GAS or LIQUID. This model comes supplied with a sensor extension rod which allows easy testing of multiple banked rows of cylinders often found aboard seafaring vessels.

  • User-friendly display, versatile and accurate to ±1.5 mm.
  • Three intelligent calibration features and four power settings for increased gain.
  • Capable of testing a wide variety of fire suppression agents, such as; CO2, FM200™, NOVEC™ 1230, old Halon agents, FE-13™, FE-25™, NAF S III™ and all core Clean Agent systems.

The Portalevel® MAX MARINE PLUS is designed to be a portable way to non-invasively locate the liquid level inside most single skinned cylinders. Our technology is suitable for many applications, but it is most widely used as a replacement for both weighing fire suppression cylinders during installation and servicing, or replacement for the fitting of internal and invasive liquid level ‘float’ devices. Once the liquid level height inside a container has been located, the agent weight can be determined using the Portasteele® CALCULATOR, which is designed to quickly convert liquid height to agent weight accounting for the cylinder size, agent type and temperature.

Converting Liquid Level to Weight: Monitoring the liquid level in fire cylinders is a vital aspect of any fire suppression system maintenance schedule, however, understanding how the liquid level relates to the fill weight of the cylinder is equally important. Coltraco Ultrasonics offer, in conjunction with the Portalevel® range, the world’s first liquid level to agent mass calculator.

The Portasteele® CALCULATOR calculates the agent weight of a fire suppression cylinder. It does this by using the liquid level determined by our Portalevel® range or inversely, by using the required fill level for a certain weight of suppression agent. The Portasteele® CALCULATOR is sold as a stand-alone unit on a 7’’ hand-held tablet to be used in conjunction with our Portalevel® range.

Operating Principle 

  • An ultrasonic transducer, either handheld or extension rod, coated in ultrasound gel (or water) generates an ultrasonic pulse that is transmitted into the fire cylinder and is reflected back. The ultrasonic gel acts as a couplant by removing any air gaps between the ultrasonic transmitter and the cylinder wall, thus allowing the transmission of ultrasound.
  • As the wave travels throughout the cylinder, some of its energy is dissipated into the cylinder and its contents. This results in the signal returned to the transducer having decreased amplitude. Analysis of the returned signal can be used to determine if the transducer has been placed in the liquid or gas phase.
  • The Portalevel® MAX MARINE PLUS will display a numerical value which is an indicator of the strength of ultrasound received by the unit.
  • The device is calibrated by moving the transducer up and down the cylinder whilst reading the numerical value off the display and engaging the ‘CAL’ button when in the appropriate section.
  • The user has the option of selecting between three calibration modes depending on the cylinder and agent type.
  • The Portalevel® MAX MARINE PLUS will now indicate which section of the cylinder the ultrasonic transducer is located by displaying GAS or LIQUID, thus allowing the user to accurately find the liquid level.

Extension Rod explained



IMO SOLAS & FSS Code Chapter

“Means shall be provided for the crew to safely check the quantity of the fire extinguishing medium in the containers.”

The crew are not qualified to dismantle the fire system to weigh the cylinders. So having a quick and easy to use ABS Type Approved ultrasonic liquid level indicator is the only accurate and efficient way of delivering better fire safety onboard, and protecting the crew.


What's In The Box

  Portalevel® MAX MARINE PLUS Unit:main electronic unit fitted with harness points for handsfree operation.
  Handheld Ultrasonic Sensor:fitted with magnetic head to ensure perfect positioning on the cylinder wall every time.
  Ultrasonic Gel:ensures perfect connection between cylinder and sensor allowing the transfer of ultrasound into the inspection surface.
  Carrying Case:robust protective case which is ideal for transportation, storage and protection in harsh environments.
  Infrared Thermometer:used to measure cylinder surface temperature.
  Extension Rod:used for testing banked cylinders in multiple rows up to four deep.
  Calibration Certificate:providing traceability of accuracy and documenting unit setup. 
  Operating Instructions:manual provides setup instructions and step-by-step guide for usage. Technical support is available for the lifetime of the product. 

Technical specifications

Technical Specification
  • Height: 160mm
  • Width: 82mm
  • Depth: 30mm
  • Weight: 300g
  • 14mm diameter magnetically mounted sensor applicator with a 1 m BNC coaxial cable.
  • 12mm width, 0.9m length slimline extension rod with mounted sensor connected with a 2.5m BNC coaxial cable

+/- 1.5 mm / +/-1/16 inch

Power Supply

1 x PP3 9V battery offering 10 hours operational battery life


55 x 28 mm backlit LCD

Operating Temperatures

-10 °C to +65 °C / 14 F to 149 F

Classifications & Approvals

UL Listed, RINA Classification Society Approval, ABS Type Approval

Enclosure Rating

IP65 Rating


CE UKAS ISO 9001, ISO 1400


Main unit – 3 Year Warranty | Sensor – 1 Year Warranty | Technical Support – Lifetime of the unit

See the Portalevel® MAX MARINE PLUS in action.

Frequently asked questions

The Portalevel® MAX MARINE PLUS can measure the level of a wide variety of liquids. The primary application is for checking the liquid level in fire suppression cylinders. These agents commonly include: CO2, FM200™, NOVEC™ 1230, Halon agents, FE-13™, FE-25™, NAF S III™ and, all core Clean Agent systems. However, the Portalevel® MAX MARINE PLUS has been shown to work on other liquids such as water, fuel, LPG and even mayonnaise in the processed food industry.
The Portalevel® MAX MARINE PLUS can identify the liquid level to ±1.5 mm of the actual liquid level. When using the Portasteele® CALCULATOR to convert the liquid level to agent weight, the results are accurate to within 1%.
With the Portalevel® Max Marine Plus, you also get an extension rod that allows you to measure the liquid level in banked cylinders up to four deep.
The Portalevel® MAX MARINE PLUS is one of the most powerful we have developed and works on a large range of cylinder sizes. We have an extensive range of products that can measure anything from 10 cm to over 15 m diameter, so get in touch to find out which unit is suitable for your application.
No, you can use any ultrasonic gel, available in most pharmacies, as well as petroleum jelly. Water will also work, but in hot environment needs very regular application.
No, unfortunately above this temperature CO2 converts into a supercritical fluid state and your cylinder will no longer have a liquid level to measure. We recommend testing CO2 in lower temperatures. Please, get in touch if you need recommendations for hot climate CO2 monitoring.
Yes, however, these agents are far more stable at higher temperatures that CO2, and although the liquid level will naturally rise with increased temperature it is far less than with CO2 and, therefore, can still be tested.
Yes, this unit is specifically designed to work despite the presence of a siphon tube.
The three calibration modes are deigned to offer greater flexibility for the Portalevel® MAX MARINE PLUS to test a wider range of cylinders, despite challenging measuring conditions. CAL 1: This is the standard setting to be used in most cases. This will work when the trend in readings you observe goes from high to low with a large drop-off CAL 2: This mode is to be used when the difference between high and low readings is great, or if CAL 1 is insufficient. CAL 3: This mode is to be used when the difference between high and low readings is small, and/or CAL 1 or 2 is insufficient.

Related Products

The Portalevel® INTRINSICALLY SAFE is an ultrasonic liquid level indicator approved for Zone 1 ATEX hazardous or explosive environments.

P/N: 2290334-IS

The Portasteele® CALCULATOR is the perfect partner to any of Coltraco Ultrasonics’ liquid level detectors. It allows you to convert your measured liquid level to an agent weight, precisely and accurately. These readings can then be saved and exported for future reference and traceability. 

Used in partnership with the Portalevel® Ultrasonic Level Indicator range 

P/N: CALC-007

The Portamarine® is a portable and battery powered, liquid level indicator designed to non-invasively, accurately, and reliably measure the level of fire suppression agent contained within a cylinder. The Portamarine® is suitable for most standard size cylinders containing CO2, Liquified Clean Agents and Halons and is specifically equipped for use onboard marine vessels and environments in the marine sector.  

P/N: 2290334-COPM
IMPA: 652777