ANSI Z21.78-2010

(reaffirmed 2020) •

CSA 6.20-2010

(reaffirmed 2020)

American National Standard/CSA Standard for Combination Gas Controls For Gas Appliances

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Revision History

ANSI Z21.78-2010 • CSA 6.20-2010, American National Standard/CSA Standard for Combination Gas Controls For Gas Appliances

Contents

Part I Construction

Page

1. Scope 1

2. General 2

3. Specific Functions 3

4. Data Furnished By Manufacturer 5

5. Connections 6

6. Threaded Fasteners 7

7. Adjustments 7

8. Electrical 8

9. Materials 8

10. Instructions 8

11. Markings 9

Part II Performance

1. General 13

2. Test Gases And Pressures 14

3. Strength And Deformation 14

4. Leakage 17

5. Electrical Characteristics 19

6. Mounting For Test 21

7. Capacity Test 22

8. Manual Valve Function 24

9. Pressure Regulator Function 27

10. Automatic Valve Function 39

11. Resistance To Permanent Damage At Excessive Supply Pressure 54

12. Automatic Ignition Components 56

13. Thermostat Function 60

14. Automatic Gas Shutoff Device Function 67

15. Main Gas Electrical Shutoff Switch 69

16. Strength Of Stops 70

17. Marking Material Adhesion And Legibility 71

Tables

Table IA Minimum Thread Length & Length To Shoulder 74

Table IB Minimum Distance From Inlet To Any Shoulder At End Of Thread

For Combination Controls Used On Cooking Equipment 74

Table II Minimum Spacing In Inches (mm) 75

Table III Minimum Spacings For Parts Connected To

Low-Voltage And Millivoltage Circuits 76

Table IV Load For Bending Moment Test 76

Table V Torques For Turning Effort Test 77

Table VI Test Conditions For External Gas Leakage 77

Table VII Allowable Valve Seat Leakage for Thermostatic Valves 78

Table VIII Test Conditions For Internal Gas Leakage 79

Table IX Torque Limits For Low Temperature Test 80

Table X 80

Table XI Allowable Outlet Pressure Tolerances 81

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Contents (Continued)

Page

Table XII Inlet Test Pressures 81

Table XIII Maximum Allowable Vent Limiter Venting Rate 82

Table XIV Maximum Temperature For Electrical Components (*1) 83

Table XV Inlet Test Pressure For Integrity Of Operation Tests 84

Table XVI Duration Of Continued Operation Tests 84

Table XVII Permissible Temperature Variation From Set Point 85

Table XVIII Number of Cycles for Thermostat Temperature Selecting Mechanism 85

Figures

Figure I Typical Arrangement of Test Apparatus 88

Figure 2. Typical Arrangement of Test Apparatus for Combination

Control with Negative Pressure Regulators 90

Figure 3. Range of Regulation Curves for Nonadjustable Regulators 91

Figure 4. Range of Regulation Curves for Adjustable Regulators 92

Figure 5. Range of Regulation Curves for Multi-Stage Regulators 93

Figure 6. Range of Regulation Curves for Nonadjustable Negative Pressure Regulators 94

Figure 7. Range of Regulation Curves for Adjustable Negative Pressure Regulators 95

Figure 8. Range of Regulation Curves for Convertible Regulators 96

Figure 9. Range of Variable Load Capacity (Typical) 97

Figure 10. Typical Curves for Evaluations in 2.9.6-e 97

Figure 11. Arrangement for Integrity of Operation Test 98

Figure 12. Integrity of Operation Curve 99

EXHIBIT A Items Unique To The United States 101

EXHIBIT B Items Unique To Canada 105

EXHIBIT C List Of Reference Standards 107

Part III Manufacturing And Production Tests 109

Part IV Definitions 111

APPENDIX A Preferred Graphic Symbols Of Commonly Used Items, Extracted From ANSI/IEEE Standard 315, Graphic Symbols For Electrical And

Electronics Diagrams, And Abbreviations For These Items 117

APPENDIX B Table of Conversion Factors 125

Note:

This standard contains SI (Metric) equivalents to the yard/pound quantities, the purpose being to allow the standard to be used in SI (Metric) units. (Standard for use of the International System of Units (SI): The Modern Metric System, IEEE/ASTM SI I0 or Metric Practice Guide, CAN/CSA Z234.1 are used as a guide in making metric conversion from yard/pound quantities.) If a value for a measurement and an equivalent value in other units, the first stated is to be regarded as the requirement. The given equivalent value may be approximate. If a value for a measurement and an equivalent value in other units, are both specified as a quoted marking requirement, the first stated unit, or both shall be provided.

x

American National Standard/CSA Standard For Combination Gas Controls For Gas Appliances

Part I: Construction

1.1 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