Wisconsin Administrative Code › Department of Natural Resources › NR 800 - Environmental Protection - Water Supply › Chapter NR 811 - Requirements For The Operation And Design Of Community Water Systems › Subchapter V - Pumping Equipment and Appurtenances › Section NR 811.34 - Pump variable output control devices

Current through June 24, 2024
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.