Open Feed & Expansion Tank (OET)

Open Feed & Expansion Tanks serve the dual purpose of:Overcoming pressure fluctuations from expansion within the system and Preventing backflow to mains water supply. This is the oldest method of expansion accommodation in closed loop systems.

Economical, reliable and convenient

There are 2 methods of combating the pressure fluctuations in a system caused by thermal and pressure changes – Atmospheric and Pressurised. The OET utilises the atmospheric method. Before the advent of closed expansion vessels, (see our Aquazone section) it was via a header tank, commonly referred to as an open expansion tank, installed at the highest point in the system. These were often large cylindrical tanks made from copper or stainless, with a ball float installed within the tank to allow water infill as necessary from an external source (mostly from town water supply). The tank would have an overflow and drain and a safe tray. Masterflow has designed a standard range to suit most applications and offers custom design tanks for space limiting situations.

Standard nominal tank capacities:

  • 35 litres
  • 60 litres
  • 100 litres
  • 200 litres
  • 300 litres
  • 500 litres
  • 650 litres

 

Features typically include:

  • Made from 304 grade stainless steel
  • Come complete with safety tray and lid
  • Approved float valve for mains supply into the tank
  • Non-metallic supports for positioning between the tank and the tray (as detailed in AS 3500) can be supplied if required. (minimum 12mm thick)
  • Wall brackets can be supplied (optional extra).

WE CAN HELP YOU CHOOSE THE RIGHT Open Feed & Expansion Tank (OET) FOR YOUR PROJECT

By designing a standard range, available either ex-stock or within a short time frame, Masterflow offers the convenience for competitive value.

Case Study

Royal Australian College of Physicians

This charming heritage building nestled between more modern 1970s style structures and stands as a monument to Sydney early Macquarie era days. Originally used as a newspaper printing facility, it is now the home to RACP. This is where overseas medical professionals come to validate their overseas training and gain Australian recognition. In July 2016 an upgrade to their existing chilled water system was approved, and the work finished in July 2018.

To correctly size what tank you require, it is important to understand the required expansion capacity of the system. Once these has been calculated using the system volume, temperatures and pressure range, a suitable tank can be selected based of its expansion capacity, not the nominal volume.

To correctly size what tank you require, it is important to understand the required expansion capacity of the system. Once these has been calculated using the system volume, temperatures and pressure range, a suitable tank can be selected based of its expansion capacity, not the nominal volume.

Frequently asked Questions

You have the following options when it comes to closed loop systems. 1. An open expansion tank is the simplest for small volumes, where the tank can be easily placed high enough above the highest point. 2. A closed expansion tank with an RPZ valve can be used anywhere that is convenient, provided it is connected to the return line of the system. Provided the mains pressure is high enough to pressurize and fill that expansion tank it will work correctly. The downside is that the RPZ valve does require regular testing. (annual testing). 3. The same expansion tank could be supplied with a refill unit which includes a break tank. This tank will protect the water supply from contamination as per the open feed tank.

No, not normally. Open Loop means there is a break to atmosphere, as it the case of condenser water circuits with cooling towers.
Because they must be installed a metre higher than the highest point of the system, OHS challenges must be navigated for initial installation and ongoing maintenance checks. Structural hardware such as platform and access ladder are required. Pressurised tanks are lot more economically priced and have lower installation costs.

ENGINEERED SOLUTIONS FOR PUMPS, TANKS, CHILLERS, FILTRATION, VALVES & CONTROLS. Get a quote or contact us today

Masterflow is and has been a trusted name among Australia’s HVAC suppliers for over 20 years. We supply a wide range of pump types and can provide the ideal solution to the many and varied fluid requirements that face the industry. We pride ourselves on remaining agile, innovative, and having fast turn arounds. We are local! All our pumps are locally designed, built and manufactured here in Australia.

Our experienced team are here to help you. Please call us on 02 9748 2022 or leave us a message on our contact form.