Quick Flush System & Filtration for Chiller Plant

Rain for Rent, Chicago received a call from a major mechanical contractor head-quartered in the Midwest. The scope of the project was to clean, flush, and filter water from a chiller plant at a major University. Because of the magnitude of the project, time constraints, and other unknown variables, a sales representative from Rain for Rent immediately visited the site to better understand the project scope.

A major University was in the process of expanding their medical facilities by building additional housing and a new hospital pavilion that would house the University's Medical Center.

To accommodate the new buildings, a new chiller plant was being constructed that required new chiller and steam lines. A chiller plant is used for cooling large buildings and industrial process applications. The system needed to be filtered and flushed after the completion of construction.

The University looked at four options: (1) pig the lines – this could not be done because the chiller line went from 36-inch to 24-inch diameter and would block the pig; (2) put a person inside the pipeline – deemed too dangerous; (3) use a machine that would go inside the lines – too expensive; and (4) flush the lines using clean water and pumps. The latter is where Rain for Rent came in.

The Rain for Rent, Chicago branch received a call from the mechanical contractor and immediately a sales representative visited the job site to evaluate the magnitude of the project. The project called for a system to flush five pipelines with a flow rate of 5 feet/second and a filtration system to remove particulates down to 20 microns.

The challenges included unknown site variables as well as finite space, time, and expected outcomes. Installation and operation in limited space required forethought, cooperation and accurate design of every piece of equipment and labor process. A team effort between Rain for Rent, the mechanical contractor, and the University were essential for a successful project.

Rain for Rent provided a system of pumps, filters and portable tanks to flush all debris and filter the water before being recirculated back into the system. The project involved two phases. The first line to be flushed was the chiller line using high flow pumps. Then the steam lines were flushed using high pressure pumps.

Although the mechanical contractor was confident in Rain for Rent's ability to perform the job, the University's engineers had to be convinced of our capabilities. After our Chicago branch manager and sales representative presented Rain for Rent's engineered solution, safety record, and history, the University awarded the project to Rain for Rent.

The system consisted of three 21,000-gallon coated Worksafe™ tanks manifolded together to hold 84,000 gallons of clean water for flushing. Three DV-300i 12-inch Power Prime™ pumps and one HH-150 6-inch high head pump were manifolded together to flow into the inlet of one 36-inch HDPE pipe for flushing at the Chiller Plant side of the project. At the east end of the pipeline, a manifold was attached to the 24-inch flange flowing through 11 BF-1000 (1,000 gpm) bag filters using 100 micron bags for the first four change-outs to remove the larger solids followed by 50 micron bags, then 25 micron bags, and finally 10 micron bags to meet the filtration design. Pipelines consisted of 6,600 feet of 36-inch HDPE pipe and 3,300 feet each of 12 inch, 8-inch and 3-inch steel line.

After the initial filtration cycle, the water from the bag filter manifold flowed back into the second 36-inch pipe, with a slipstream flowing through a Portable Water Quality Monitoring System (PWQMS) to ensure filtration specifications were met. The water came back to the chiller plant through another series of 11 BF-1000 (1,000 gpm) bag filters, using the same filtration method, working from 100 micron down to 10 micron bags. The water then traveled into a third manifold through the rear of the tanks, after flowing through a second PWQMS to check outflow before the system sent water to re-circulate.

After the chiller pipe had been flushed, one 8-inch extra high-head pump flushed out the 12-inch, 8-inch and 3-inch steam pipes using the same process.

Specific instructions were developed to ensure the safest and most efficient sequence of equipment delivery, installation, and disassembly. Rain for Rent staff taught procedures for starting, operating, maintaining, and monitoring equipment and flow. All equipment had shut-off valves in the event that any piece had to be isolated.