UL 921 PDF

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 is not intended to be used to evaluate the gas-fired water heating portions of the system that incorporate water containment vessels operating above atmospheric pressure.

For dishwashers that incorporate a gas-fired water heater with a pressurized water containment vessel operating above atmospheric pressure, the water heater portion of the system is covered by the requirements of ANSI Z21.10.3/CSA 4.3.

1.3 This Standard covers:

1. a) electric dishwashers rated 600 V or less, installed in accordance with the Canadian Electrical Code (CEC), Part I , CSA C22.1, and the National Electrical Code (NEC), NFPA 70; and

2. b) the gas-handling, gas-burning, and gas-control features of gas-fired dishwashers having inputs of 420 MJ (400,000 Btu per hour or less, limited to 3.45 kPa (0.5 psig) 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. 1) natural gas;

   2. 2) manufactured gas;

   3. 3) mixed gas;

   4. 4) propane gas;

   5. 5) liquefied petroleum gases; or

   6. 6) LP gas-air mixtures.

1.4 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.

Summary of Topics

This reaffirmation of ANSI/UL 921 dated December 17, 2024 is being issued to update the title page to reflect the latest ANSI approval date as a Reaffirmed American National Standard (ANS). No changes in requirements are involved.

As noted in the Commitment for Amendments statement located on the back side of the title page, ULSE and CSA are committed to updating this harmonized standard jointly. However, the revision pages dated December 17, 2024 will not be jointly issued by ULSE and CSA as these revision pages only address UL ANSI approval dates.