UL 921

Please note: All interim revisions for this edition available at time of your purchase will be included.

Commercial Dishwashers
UL 921
1 Scope

1.1 This Standard covers commercial, freestanding, under-counter, and counter-insert dishwashers, utensil-washers, and glass washers using water as the principal cleaning medium, hereafter referred to as dishwashers. These dishwashers utilize steam, gas, or electric heaters for heating the water. Heated water is provided to a dishwasher by means of steam, gas, or electric heating systems integral to the appliance, or by means not integral to the dishwasher that is provided at the installation site.

1.2 This Standard covers:

• a) electric dishwashers rated 600 V or less, installed in accordance with the Canadian Electrical Code (CEC), Part 1, CSA C22.1, and the National Electrical Code (NEC), NFPA 70; and
• b) the gas-handling, gas-burning, and gas-control features of gas-fired dishwashers having inputs of 400,000 Btu (420 MJ) per hour or less, limited to 0.5 psig (3.45 kPa) inlet pressure, installed in accordance with the National Fuel Gas Code, ANSI Z223.1/NFPA 54, the International Fuel Gas Code, ICC IFGC, or the Natural Gas and Propane Installation Code, CSA B149.1 for use with:
  • 1) natural gas;
  • 2) manufactured gas;
  • 3) mixed gas;
  • 4) propane gas;
  • 5) liquefied petroleum gases; or
  • 6) LP gas-air mixtures.

1.3 These requirements cover dishwashers intended for use in commercial establishments, such as kitchens of restaurants and hospitals, where they are not intended to be accessible to the public.