Guidelines on when to use a SUBMERSIBLE PUMP versus a Vertical Turbine Pump:
There are two main laws currently in place which specify that iron and steel products must be sourced from within the United States; the American Iron and Steel requirement and the Steel Products Procurement Act.
Projects funded through the Clean Water State Revolving Fund (CWSRF) and the Drinking Water State Revolving Fund (DWSRF) contains the American Iron and Steel (AIS) requirement. This requirement specifies that iron and steel products be produced within the United States. Per a memorandum issued by the United States Environmental Protection Agency (EPA), “Implementation of the American Iron and Steel provisions of P.L. 113-76, Consolidated Appropriations Act, 2014” any item which is not specifically listed is excluded and may be produced outside the United States even if it is primarily iron or steel. Neither a pump nor a motor is a listed item. Furthermore, it is clarified that mechanical and electrical components, such as pumps and motors, are excluded.
Public works projects in the state of Pennsylvania are required to meet the Steel Products Procurement Act which is commonly referred to as the Pennsylvania Steel Act. This act requires that at least 75% of the steel products be sourced from within the United States. This act notes that there is a list of exempt machinery and equipment which is updated annually. The current list of exempt machinery and equipment from the Department of General Services (DGS) contains five types of pumps which are excluded. This specifically lists turbine and submersible pumps.
While the American Iron and Steel (AIS) provision and Steel Products Procurement Act (Pennsylvania Steel Act) may be specified for a municipal project, both contain exemptions for the pump and motor.
For further information, please refer to the following:
American Iron and Steel (AIS)
Steel Products Procurement Act (Pennsylvania Steel Act)
Yes, National Pump stocks both 304 & 316 grade stainless steel impellers, up through 15” designs with NO performance corrections.
Yes, National Pump has NSF61 & NSF372 certification on the pump / bowl assembly, using the materials that were used to certify the pump. If any component is deleted, added or provided with a material change, it can no longer be considered ‘certified.’ If 300 series stainless steel materials are used in place of, or in addition to those used to certify the pump, the pump can only be considered ‘compliant.’
Yes, all pumps that are required to be built to the ISO9001 certification must be manufactured at National Pump’s ISO 9001 certified plant in Glendale, AZ.
National Pump manufactures pumps in a variety of materials to meet our customer’s preference or needs. Bowls and Impellers are available in Cast or Ductile Iron, Cast Steel, Stainless Steel, a variety of Bronzes or Duplex Stainless Steels. Bearing materials are available in Bronze, Marine rubber, and engineered composites.
Every piece of rotating machinery (motor, pump, etc.) has a natural frequency or vibration of operation. As the discharge head of the pump supports the motor, it is the responsibility of the pump manufacturer to design the discharge head to withstand the natural frequencies of the motor through its operating speed range (say 45 – 60 HZ, or 1350 – 1800 rpm). Reed Critical analysis is a calculation that is done that looks at the motor frequency and its effect on the stability of the fabricated head and motor structure. Design adjustments are made to the fabricated head to insure vibration free service. (See story on Tacoma Narrows Bridge failure in 1940)
When using a cast iron discharge head, National Pump Company can only guarantee vibration free operation at full load speed. A cast iron discharge head may be acceptable for operating at reduced speeds if precautions are made by locking-out the operating speed(s) on the VFD IF vibration is experienced from the natural resonant frequency of the motor and discharge head structure. In some cases, modifications can be made to the discharge head to change the resonate frequency of the structure.
Normally catalog performance and efficiencies are ‘best obtainable’ performance derived from testing using standard materials of construction (i.e. Cast Iron Enameled lined bowls & Bronze impellers) with backfilled and highly polished impellers. Any material change or use of a ‘standard’ polish, may reduce pump performance. The Hydraulic Institute sets performance standards and test tolerances for what a manufacturer can or cannot provide. These standards range from – 9% to +16% deviation on Flow, – 7% to +10% on Head, -7% to 0% on efficiency. When specifying a pump, it is important to define early on what your expectations are so that the manufacturer can meet those expectations. Call a National Pump Representative to learn more about the Hydraulic Institute Test Tolerances.
Yes, this info is available in our IOM Manual located on our web site. The preferred levelness is dead level, however, an acceptable tolerance is 0.002 inch per foot. For deep well applications, the leveling of the discharge head is often installed to fit the well straightness, which may exceed the 0.002 inch per foot guidelines.
NPSHR is the minimum pressure required at the first impeller of the pump to keep the pump from cavitating (i.e. turning water to water vapor in the pump). This differs from NPSHA (available) which is the absolute pressure at the pump suction. Both values are represented in ‘feet’ of pressure. NPSHA must be a minimum of 3 feet more than NPSHR.