Section NR 811.34 - Pump variable output control devices Installations where pumps and pump motors will be physically or electronically controlled by a variable output control device shall meet the following requirements:
(1) PUMPING CAPACITY TO MEET PEAK DEMAND. The gallon per minute discharge rates of the pump or pumps shall be capable of meeting the peak demand rate when there is no elevated storage and the pressure tank storage volume will be reduced due to the installation of the variable output control device or devices.(2) HIGH PRESSURE CUT-OUT SWITCH. A high pressure cut-out switch shall be installed on the pump discharge piping to stop the pump motor when a preset maximum discharge pressure is detected if the pump shut-off head at the maximum possible speed will exceed the safe working pressures of the piping and appurtenances.(3) PRESSURE RELIEF VALVE. A pressure relief valve shall be installed on the pump discharge piping sized to allow adequate pressure to be relieved if a malfunction that would cause the pump to discharge at the maximum possible rate would result in pressures exceeding the safe working pressures of the piping and appurtenances.(4) BACKUP CONTROLS. All water systems supplied by one well or booster pump shall be provided with a redundant means of controlling the operation of the pump motor. Such means may include the installation of an electrical bypass of the variable output control device along with the installation of pressure switches or other department approved installation.(5) FLOW PACING FOR CHEMICAL FEED PUMPS. Where pump discharge rates will vary after initial startup of the pump, all chemical feed pumps shall be paced from a flow proportional signal from a water meter. This requirement is in addition to any requirement for the chemical feed pump to be wired to operate in series with the pump motor starter and any required secondary chemical feed pump control mechanism.(6) ADEQUATE STORAGE. Storage shall meet the following requirements when there is no elevated storage or the minimum pressure tank storage volume normally required by s. NR 811.61 (7) will be reduced due to the installation of one or more variable output control devices. (a) For other-than-municipal water systems and small municipal water systems not provided with elevated storage, the gross pressure tank storage volume shall be a minimum of 2.5 times the design pump output in gallons per minute. When a vertical turbine pump requiring prelubrication or an auxiliary power source with an automatic transfer switch is employed, calculations shall be provided to the department to demonstrate that the storage volume is adequate to provide the necessary time for the prelubrication to occur or for the auxiliary power source to come on line before the system pressure drops below 20 psi as a result of a brief electrical power outage.(b) For a control valve type of installation, the gross pressure tank storage volume shall be a minimum of 5 times the design pump output in gallons per minute to prevent the pump motor from over-heating.(c) For booster or high-lift pump installations where the pump is discharging to a distribution system without elevated storage, the gross pressure tank storage volume shall be a minimum of 2.5 times the design pump output in gallons per minute.(d) As an alternate to pars. (a) to (c), the department may approve other proposed pressure tank storage volumes when justified by supporting information submitted to the department.(e) Control or piping and valve measures shall be provided to prevent water from becoming stagnant in pressure tanks. The variable output control device shall be programmed to allow a 10-psi pressure drop from pump 'off' mode to pump 'on' mode to allow time for the pressure tanks to empty.(f) Additional storage volume shall be provided for adequate operation of water treatment equipment including storage volumes necessary to obtain required reaction or disinfection detention times in detention vessels. The storage volumes shall be calculated by the design engineer assuming the pump or pumps are discharging at the maximum possible rate.(7) VENTILATION. Automatically controlled forced air ventilation shall be installed for any room where an electronic variable output control device will be installed and room temperatures will exceed 90 degrees F.(8) MEASURES TO PREVENT DAMAGE FROM CORROSIVE CHEMICALS. The installation of an electronic variable output control device may not be allowed in a corrosive environment. Electronic variable output control devices may not be installed in the same room with fluoride acid chemical feed equipment. Preventive measures such as adequate sealing and ventilation of chemical containers and solution tanks shall be taken to minimize the production of corrosive fumes from other kinds of chemical feed installations, including sodium hypochlorite. The installation of a separate chemical feed room or the installation of room or chemical feed system ventilation improvements may be required by the department where significant damage from corrosive fumes has been documented.(9) DEHUMIDIFICATION OR AIR CONDITIONING. Dehumidification or air conditioning equipment shall be installed in any room where an electronic variable output control device will be installed and excessive moisture will be a concern.Wis. Admin. Code Department of Natural Resources NR 811.34
CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.Amended by, CR 22-074: am. (6) (e) Register January 2024 No. 817, eff. 2/1/2024