TECHNICAL BULLETINS

Drass Technical Bulletins are released to support/improve Drass equipment currently in operation.

2'' FLOW FUSES

Drass continued R&D activities finalized an improved design of 2” Flow Fuses used within all saturation diving compartments on in&out lines connected to the ECUs.
The improvement consists in the replacement of the existing 2” Flow Fuses with new one; the benefits are listed below:
1. Greatly Improved noise reduction, due to the completely redesigned shape and filtration mesh;
2. Improved immunity to gas flow peaks, produced by improper opening of the ECU segregation valves; with this new design such peaks will be managed by the flow fuse avoiding any unwanted closure.

CLAMP WEIGHT

Request for the opening of one symmetrical gate on the upper side of the Clump Weight structure.

HYDRAULIC POWER PACK

Thermal protection for both HPP electric motors are to be replaced with lower rating components.

GUIDE WIRE SECURING DEVICE

Guide Wire securing device on Diving Bells can be upgraded in terms of reliability.

LIFEBOAT IFG REGULATOR

The CCU of the Flywheel Generator has been modified to meet nowadays requirements.

BELL WINDOW SEALING

Drass has improved the diving bell window protection with a double gasket and a new outer flange on each side of the window.

BELL LARS HANDLING SYSTEM

The CCU of the Flywheel Generator has been modified to meet nowadays requirements.

COMPAIR COMPRESSOR SAFETY IMPR

The improvements suggested are intended to avoid safety issues caused by oil contamination by breathing gas when the compressor is working in vacuum and therefore there is potential pulling of oil through the seals.

EMERGENCY SCRUBBER

DRASS performed an extensive testing program of Emergency Scrubbers to evaluate endurance and capabilities in terms of carbon dioxide removal.

ECU THERMAL PROTECTION

The upgrade is recommended to avoid safety issues due to; wrong human management of gas circulation from the ECU to the chambers; accidental flow fuse shut off, or wrong valve configuration set up.

DIVING BELL PASSIVE CURSOR

The scope of this modification is to optimize the diving bell’s ballast maintenance and control from the Moon Pool and Mating clamp position when the Diving bell is inserted inside the Passive Cursor.

BELL FOOD LOCK INTERLOCKING

The new diving bell food lock interlocking mechanism can be upgraded in terms of reliability, adding a system that has improved the level of protection against water entry, thereby preventing food lock flooding during deployment.

ECU 3 WAY VALVES

In order to ensure that no leaking occurs at ECU cross connection valves, Drass suggests the installation of a kit on ECU gas lines, close to the 3-way valves.

O2 ANALYZER CALIBRATION LINES

Drass has studied and developed an easy and safe system for the calibration of oxygen analyzers. This improvement increases the safety of technical personnel responsible for calibration because portable sample bottles are not required and the risk of using a non-certified gas is reduced.

ECU SOFTWARE UPGRADE

The modifications Suggested are intended to improve the level of functioning of the Environmental Control Unit (ECU) & HMI as per the following points:
A. improve capability to control DDC temperature to one tenth of a degree.
B. improve capability for quick control of the environment in shallow water conditions (with a dedicated button on the HMI).
C. improve ability for quick dehumidification in DDC (with a dedicated button on the HMI).
D. Improve analysis tools such as temperature and humidity graphs.

INNER DOOR HANDLES

Drass recently improved the design of the inner chamber door handles; This improvement is offered to customers of operational Diving Systems manufactured by Drass. The aim of this modification is to improve levels of safety regarding the use of the inner chamber doors.

TESCOM REGULATORS

Tescom pressure regulators installed on f.a.v.a. panel (bell gas management panel) can be subject to salty gas flow, which could damage the metallic parts and gaskets of the inner regulator.

BELL HANDLING CONTROL CONSOLE

The improvements Suggested are intended to improve level of functioning of the bell handling HMI
– improving alarm presentation and alarm acknowledge.
– preventing possible error in the installation of a PLC or HMI software module where the incorrect version of the software has been previously installed.
– adding Shock Absorber pressure alarm
– preventing improper use of solenoid activation for the consent of bell mate trunk pressurization.

GRAPHITE SEAL IN VALVES

Drass has verified a better performance of the valves PN 46SD2009 / 46SD070 mainly used in recirculation of aerating gas (ECU lines), by replacing the graphite seals to ptfe.

BELL INNER GAS SUPPLY

Drass studied a solution to improve the arrangement of Bell inner gas supply emergency device – to better clarify, the group of devices intended to alert the stand by diver inside the bell in case the supply of gas from the surface (via the main umbilical) is missing, and then the system had automatically changed over to the bell on board gas storage.

ECU CONDENSATION DRAIN

An improvement for A0901-xxx and A0902-xxx ECUs has been identified in relation to the reliability of the condensation discharge function.

BPR WATER STAGNATION

If there is stagnation of water inside the BPR of the Water Trap, it could happen because the BPR is installed in vertical position.

MAIN WINCH BRAKE CYLINDER

Some replacement cylinders have been found to have a difference in dimension between the mounting lug and the cylinder fork. It is necessary to check the dimension and ensure that alignment between parts is correct.

NEW TROLLEY PLIERS

The new trolley pliers allow the bell to engage without any opening command thanks to an advanced internal profile, shaped and tested in Drass laboratories.

CONNECTING TRUNK PRESSURE CONTROL

The new configuration proposed allows the pressurization and depressurization of the spool by an external valve system.

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