Backflow preventionTest Kit

In order to get a useful amount of gaseous fuel into a reasonably-sized tank, you have to liquify it. Some fuels are easier to liquify than others. According to the textbook Organic Chemistry by Joseph M. Hornback, propane has a boiling point of -44° F (-42° C) at atmospheric pressure, but methane (natural gas), has a boiling point of -260° F (-162° C) at atmospheric pressure. This means that methane has to be cooled to a much lower temperature than propane in order to be turned to a liquid that can be stored in a tank. Propane molecules consist of three carbon atoms bonded in a chain with eight hydrogen atoms bonded to these carbon atoms. In contrast, a methane molecule is just one carbon atom bonded to four hydrogen atoms. Methane molecules have a high degree of symmetry. As a result, they do not have a permanent electric dipole. Bonding between permanent dipoles is the dominant bonding mechanism between molecules as they liquify for many substances such as water. Methane's symmetry, and therefore lack of a permanent electric dipole, means that its molecules can only bond through a much weaker effect known as the London dispersion force or the van der Waals force. In this effect, molecules induce temporary dipoles in each other, and these dipoles then bond. Because this bonding mechanism is so weak, the methane molecules have to be cooled to a low temperature until they are still enough to bond and form a liquid. In contrast, propane does not require as low a temperature to liquify.

If the pressure in the pipes is reduced, it’s possible for contaminated water from your property to be drawn back into the water supply system. This is called backflow.

Backflow preventiondevice cost

If you’re a licensed plumber with backflow accreditation, we encourage you to use and return these forms for each of your backflow projects.

Backflow can pose a public health risk if pollutants or contaminants such as chemicals enter the drinking water supply from your property.

Backflow preventiondevice Bunnings

Read about what’s required for backflow prevention, device testing and backflow risk ratings in our Backflow prevention containment policy.

If you require a backflow plumbing contractor for this work please visit the Backflow Prevention Association website, the Master Plumbers website or South East Water’s Priority Plumbing website.

Backflow preventiontesting

Most residential properties will be considered low risk properties. Devices installed in high or medium risk properties need to be registered with us, and tested at least annually by a licensed plumber endorsed for backflow prevention testing. This testing requirement is for:

South East Water proudly acknowledges the Traditional Owners of the land on which we work and live, and pay respect to their Elders past, present and emerging. We acknowledge their songlines, cultural lore and ongoing connection to the land and water. We recognise and value the rich cultural heritage and ongoing contributions of Aboriginal people and communities in our society in Victoria.

A backflow prevention device allows water to enter the property through the water meter, and prevents water from flowing back into the water supply network.

Water usually flows to your property at a consistent pressure, so you’ll have the same water pressure from your taps and fixtures every day.

Backflow preventiondevice bidet

But household propane is not usually kept in a liquid state by a low temperature. Instead, high pressure is used. In order to keep propane a liquid at room temperature (70° F or 21° C), it has to be held in a tank at a pressure of about 850 kPa. This can be accomplished with a strong metal tank. In contrast, to keep methane a liquid at room temperature requires a tank that can maintain a pressure of about 32,000 kPa. Household metal tanks cannot withstand this pressure. In short, methane is not stored in household tanks because the symmetry of its molecule makes it hard to liquify. You could in principle store methane in a tank in the gas state, but methane has such low density in the gas state that you could not store a usable amount. Instead, natural gas is processed and stored at refinery plants and then pumped to households in the gas state through pipes. The properties of different basic fuels are summarized below, showing nicely the trend in room temperature liquid pressures. Note that the pressures are approximate.

Topics: fuel, liquid, methane, natural gas, phase, phase diagram, pressure, propane, propane storage, propane tanks, vapor pressure

By: Christopher S. Baird, author of The Top 50 Science Questions with Surprising Answers and Associate Professor of Physics at West Texas A&M University

All water service connections need to be fitted with an appropriate containment backflow prevention device to protect the water supply network and our customers.