Clever ways to manage the risk of pathogens like Legionella and Pseudomonas in water distribution systems

INTRODUCTION

Horne Engineering Ltd are pioneers in the field of thermostatic control engineering, inventing, in 1909, the self-acting control valve to regulate the temperature of steam calorifiers – a world first. Another world first came in the early 1920s with the invention of the Thermostatic Mixing Valve (TMV) to accurately blend hot water with cold to provide safe and comfortable water for bathing and showering.

With the discovery of Legionella bacteria and its associated respiratory disease, Legionnaires Disease, a thermal regime, paired with point-of-use TMVs was determined the most effective method to mitigate the problem whilst also addressing the scalding risk.

In recent years, a new problem has emerged that relates to antibiotic-resistant and opportunistic microorganisms and their proliferation in domestic water supplies of institutional environments – especially in healthcare, but also education, prison accommodation and sports and leisure facilities.

The ‘dead-leg’ drop to every tap or shower outlet between the TMV and the terminal fitting ranges in temperature from ambient to that of the TMV setting favourable conditions for bacteria to multiply. The unavoidable air-water interface of the terminal fitting is also inherently vulnerable to retrograde contamination from the local environment. Now, Horne Engineering has developed yet another World First with the invention of the In-Line Thermal Disinfection Unit (ILTDU), which specifically addresses this problem.

EXTENDING THE THERMAL REGIME

PROBLEM

Via the incoming water supply and by retrograde contamination, Pseudomonas, Legionellae and other pathogens can colonise the last two metres of domestic water supply pipework, including the outlet fitting (TMV, tap or shower). This problem is specifically described in the UK Department of Health’s Addendum to Health Technical Memorandum 04-01 and in the enHealth (2015) Guidelines for Legionella control in the operation and maintenance of water distribution systems in health and aged care facilities, published by the Australian Government.

SOLUTION

The In-Line Thermal Disinfection Unit (ILTDU) facilitates periodic high-temperature thermal disinfection using the readily available hot water supply. Now the thermal regime can be extended to the point of water discharge: therefore, the wetted surfaces of all downstream components, including the TMV and the outlet fitting, can be raised to system temperature.

HOW IT WORKS

When not in use (Passive Mode), hot and cold water flows to the mixing valve and downstream fittings uninterrupted. The operation key transfers the mechanism into Disinfection Mode; diverting hot water at system temperature to the cold water supply pipe drop.

Simultaneously, the cold water supply is closed. Hot water at system temperature is now able to permeate all wetted parts of the system downstream of the ILTDU until such times as the key is turned back to the passive position.

**DISCLAIMER: As MAG's policy is one of continuous product improvement, changes to specifications may be made without prior notice. Images in this booklet have been modified and may not be true representations of the finished goods.**

Talk to us today to find out more about our "MAG-Horne ILTDU” products and to discuss specific requirements for your projects call (03) 9399 8444 or email [[email protected]]

Warm Regards,

The MAG Team