project
55
This was designed as a complete inline system, cutting into the main municipal feed after the water meter. This solution was designed by Warren Burger, business development manager at Burgess and Partners, who has been with the company for seven years now. He also managed the on-site project, making sure everything ran according to plan.
They cut the main water supply on both sites and installed the six tanks. They then connected the pumps before joining it back into the main line.
It has been designed so the whole institution runs of these backup systems continuously. As such, water stagnation does not happen, explains Burger.“ Because there is water coming in and out of the system continuously, the water gets circulated and aerated.”
The six tanks used on this site are JoJo tanks and the company was a great help in delivering the tanks directly to site, Burger explains.
The client specified the tank sizes but nothing else. The rest was up to the Burgess team, who did all the design and plumbing themselves. They even built the concrete splints and dug the trenches.
An important part of the project was installing a bypass on the system with the help of three gate valves.“ So, if for whatever reason there is no electricity to the pump( like during power cuts), or if you have to service the pumps, or there is a leak and you have to isolate the system, then you can bypass the tanks using the valves,” Burger explains.
The tanks are connected at the bottom and they fill up at the same time. The water supply comes in from the top, which is connected to a single two-inch Cobra ball valve that controls the water level inside the tanks. At the bottom of the tanks, there are 40mm outlets that connect the tanks. They are connected with 50mm uPVC pipe. For them to fill up simultaneously, it was vital that the concrete slab on which the tanks are positioned is 100 % level so the water can come in and out at the same level.
The Burgess site team dug the trenches about 1m deep by hand to install all the piping underground. In total, both sites had about 50 – 60m of pipework.
Burgess had a team of six crew members working on both sites. Both sites were run at the same time and took about three weeks to complete from start to finish. This includes pouring the concrete, digging the trenches— everything.
Pumps HMS pumps in Wadeville, Germiston, supplied the pumps. They design, supply, and install pumps. HMS specified exactly which pumps were needed for the project.
On the smaller site( JW Luckhoff), a Pentax booster pump 2.2kW( 230V) was installed and at the other school( Emmasdal), two 2.84kW( 230V) Pentax pumps were installed.
Both were installed complete with run-dry protection. The system comes equipped with a float switch, so if the tanks run empty, the float switch kicks in and prevents the pump from burning out. It will disconnect the pumps if this happens.
The pumps were selected only after the calculations were done, considering things like the size of the properties, the number of users( headcount), the type of system, and the type of services this must feed( what type of toilets and how many showers, for example), among others.“ We knew we had to run an average of 4 – 5 bar of pressure across a certain distance with a certain pipework,” explains Burger. So, from that the pumps were sized accordingly.
Switching over Thanks to the bypass, there was no downtime when the crossover was done. It was just a matter of opening one valve to let the tanks fill up, but also keeping the valve open through the bypass so the property would still have water while the tanks filled up.
When the tanks are at the correct level to pump water to the building, the bypass valve is closed, the valve at the pump is opened and instantly, it switches over and the pump kicks in and takes over.“ Here it’ s important to keep an eye on whether all your fittings are
Continued on page 57 >> www. plumbingafrica. co. za April 2017 Volume 23 I Number 2