In rural areas where the municipal water supply is inaccessible however, the process can be decidedly more rigorous.
The Central Lakes Cooperative fertilizer plant in Atwater, Minnesota, is just such an example. At 1115 m2, the facility was required to install a sprinkler system according to Minnesota State fire code. However, being too far from the municipal water supply, the system would have to be served by a well. CLC looked to Mike Steffl of Steffl Drilling and Pump to drill the well and provide the necessary components to meet the requirements of the fire code. The typical solution in this case required installing a 380 m3 reservoir to ensure adequate water capacity for the system. This reservoir would not only require a large excavation and a significant amount of concrete, but would also take up a lot of space. Mike contacted Brian Peterson of Schwab, Vollhaber and Lubratt, Inc. to see if a better solution could be achieved using a variable frequency drive. Working closely with the state’s fire marshall and electrical inspector, Brian and Mike were able to implement an innovative solution that was far more cost-effective, reliable, and compact than the traditional alternative.
In the CLC plant, when the sprinkler system is triggered by a high heat condition, a 55 kW VLT® AQUA Drive connected to the system switches from its usual parameter setup to another setup that is specified for fire mode. The drive runs a submersible pump, which pumps water into the sprinkler system at 70 PSI with a flow rate of 285 litres per minute. One of the advantages of this configuration is that the drive and submersible pump can serve not only the fire suppression system, but can also be used for plant processes, since both systems of pipes are interconnected. Under normal operating conditions, the drive runs the pump to supply the plant’s water piping with 20 PSI and a flow rate of 750 litres per minute. When a fire breaks out, a valve closes to isolate the regular water piping from the higher pressures required for the fire suppression system.
“All of the intelligence is built into the drive, rather than relying on external devices”, says Brian Peterson, “which makes for a very compact system”. The installation is one of the first of its kind, but with cost savings of over $70,000, it’s likely that many more like it will follow.
Brian Peterson of SVL is working with Mike Steffl and other partners and the Minnesota state fire marshall to amend the state’s fire code to recognize this technique as a reliable and effective system for fire suppression. As Mike Steffl points out, “it’s important not only to have the technology that makes solutions like this possible, but also the people on your team with the knowledge and expertise to be able to make it happen.”
