ANSI Z21.20-1997

Scope

1.1.1 This standard applies to newly produced automatic gas ignition systems (see Part IV, Definitions) and components constructed entirely of new, unused parts and materials.

An automatic gas ignition system shall perform the following functions:

(a) Ignite the gas at the main burner(s), or at the pilot burner(s) so it can ignite the main burner(s);
(b) Prove the presence of either the ignition source, the main burner flame, or both; and
(c) Automatically act to shut off the gas supply to the main burner(s), or to the pilot and the main burner(s), when the supervised flame or ignition source is not proved.

Components sumbitted for examination under this standard shall perform one or more of the above functions.

1.1.2 This standard applies to automatic gas ignition systems which also serve as oxygen depletion safety shutoff (ODS) systems (see Part IV, Definitions).

1.1.3 This standard covers automatic gas ignition systems and components intended primarily for use with gas appliances having inputs of 400,000 Btu per hour (117 228 W) or less per individual combustion chamber.

1.1.4 This standard applies to automatic gas ignition systems and components for use with one or more of the following gases:
(a) Natural;
(b) Manufactured;
(c) Mixed;
(d) Liquefied petroleum; and
(e) LP gas-air mixtures.

1.1.5 Compliance of an automatic gas ignition system or component with this standard does not imply that such a system or component of such a system is acceptable for use on gas appliances without supplemental tests with the device(s) applied to the particular appliance design.

1.1.6 Each component of an automatic gas ignition system shall be capable of operation throughout a temperature range of 32°F (0°C) to 125°F (51.5°C) unless either higher, lower, or both higher and lower temperatures are specified by the manufacturer.

1.1.7 The tests specified herein are to verify performance within the manufacturer's specified maximum and minimum timings where applicable:
(a) Flame-Establishing Period;
(b) Flame Failure Response Time;
(c) Flame Failure Reignition Time;
(d) Recycle Time;
(e) Lockout Time;
(f) Purge Time;
(g) Ignition Activation Period;
(h) Igniter Proving Time;
(i) Trial For Ignition Period; and
(j) Valve Sequence Period.

The above terms are defined in Part IV, Definitions.

1.1.8 If a value for measurement as given in this standard is followed by an equivalent value in other units, the first stated value is to be regarded as the specification.

1.1.9 All references to psi throughout this standard are to be considered gage pressures unless otherwise specified.

1.1.10 Exhibit A (List of Reference Standards) contains a list of standards specifically referenced in this standard and sources from which they may be obtained.