Preface:

This publication represents a basic standard for safe operation, substantial and durable construction, and acceptable performance of a combination gas control for gas appliances. It is the result of years of experience in the manufacture, testing, installation, maintenance, inspection and research on combination gas controls for gas appliances designed for utilization of gas. There are risks of injury to persons inherent in appliances that, if completely eliminated, would defeat the utility of the appliance. The provisions in this standard are intended to help reduce such risks while retaining the normal operation of the appliance.

Scope:

1.1.1
This standard applies to newly produced combination gas controls (see Definitions, Part IV), hereinafter referred to as controls, constructed entirely of new, unused parts and materials.

1.1.2
The combination control may include other functions such as pilot gas filters, pressure switches, etc., which shall be of an approved type (see Definitions, Part IV), or shall be investigated as an integral part of the combination control for construction and performance equivalent to an approved type.

A control which incorporates two or more automatic valves and no other function, (as defined by combination control, see Definitions, Part IV), may be tested to this Standard or Automatic Valves for Gas Appliances, Z21.21 • CSA 6.5, at the discretion of the manufacturer.

1.1.3
Compliance of a combination control with this standard does not imply that the combination control is acceptable for use on gas appliances without supplemental tests with the combination control applied to the particular appliance design.

1.1.4
This standard applies to combination controls having a maximum operating gas pressure of 1/2 psi (3.5 kPa) with one or more of the following fuel gases: natural, manufactured, mixed, liquefied petroleum and liquefied petroleum gas-air mixtures.

1.1.5
This standard applies to combination controls which are capable of operation in ambient temperatures of 32°F (0°C) to 125°F (51.5°C), unless a higher temperature, lower temperature or both, are specified by the manufacturer.

1.1.6
Exhibit A, Items Unique to the United States, contains items unique to the United States.

1.1.7
Exhibit B, Items Unique to Canada, contains items unique to Canada.

1.1.8
Exhibit C, List of Reference Standards, specifically referenced in this standard, and sources from which these reference standards may be obtained.

1.1.9
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.

1.1.10
All references to psi through this standard are to be considered gauge pressure unless otherwise specified.