ANSI Z21.87:2007 pdf download.Automatic Gas Shutoff Devices For Hot Water Supply Systems.
2.2 Shutoff And Reset Temperatures
2.2.1
A gas shutoff device shall operate to shut ott the gas supply within ± 10°F (5.5°C) of the manufacturers specified shutoff temperature, but in no case at a temperature greater than 210°F (99°C).
A gas shutoff device of other than the single-use type shall automatically reset or shall function to be manually resettable at a temperature not lower than 1 20’F (49°C).
Method of Test
Four devices shall be simultaneously tested installed on a suitable water bath. The four samples are to be provided with individual thermocouples complying with the next paragraph. The temperature sensing element of an immersion type of device shall be immersed in the water as in normal installation. A surface contact type of device shall be attached to the exterior of a side of the bath formed on a radius of 6 in (152 mm) with the temperature sensing element in contact with that surface, A 2 in (50.8 mm) thick pad of glass wool insuLation extending at least 2 in (50,8 mm) beyond the device shall be placed directly over the device.
Operating temperatures shall be determined with a single No. 24 AWG (0,20 mm’) thermocouple for each device. With immersion temperature sensing elements, the thermocouple shall be placed as close to the element as possible opposite the midpoint of its length. With surface contact temperature sensing elements, the thermocouple shall be silver-soldered to the interior surface of the bath immediately opposite the location of the geometrical center of the element.
The opening of an electrical circuit within a device is to be determined by any suitable means connected in a circuit typical of that in which the device is to be used.
The bath shall be filled with water and heated until the four test thermocouples indicate an average temperature 20F (11°C) less than the manufacturer’s specified shutoff temperature. The rate of heating then shall be controlled to cause a temperature rise of not less than 1°F (0.5°C) not more than 2°F (1°C) per minute. The temperature indicated by a test thermocouple at the instant the corresponding device functions shall be recorded.
‘Mth devices of other than the single-use type, the means for heating the bath shall then be shut off and cold water admitted in such a manner that it does not flow directly against the side of the bath in which the devices are installed. As the average temperature indicated by the test thermocouple approaches the reset temperature, the flow of water shall be controlled to cause a temperature decrease of not more than 1°F (0.5C) per minute. At the instant the indicated temperature for each device reaches 120”F (49’C), the device shall have reset or shall have functioned to be resettable.
One determination of shutoff temperature and, if applicable, one verification of reset operation for each device shall be made. All shall comply.
The gas shutoff device shall be installed on a suitable automatic storage type water heater In accordance with the manufacturers installation instructions (see 1.12.2).
The automatic storage type water heater shall be equipped with a control which will permit adjustment for a water temperature of 220± 5°F (104.5 ± 3°C). A thermocouple or thermometer shall be installed 3 In (76.2 mm) below the top of the storage vessel for measuring the temperature of the stored water. The Input rating or the water heater shall be adjusted so that the water temperature rise within the storage vessel Is not less than 4F (2°C) nor more than 5°F (3°C) per minute.
The automatic storage water heater shall then be filled with water at a temperature of less than 140°F (60°C), Some water shall then be drawn from the hot water outlet, after which the hot water outlet shall be Closed.
The burner of the water heater shall be operated until the temperature of the stored water 3 in (76.2 mm) below the top of the storage vessel reaches 140 ± 5°F (60 ± 3°C). The burner shall then be shut oft for a period of 15 minutes. The water heater control shall then be set at 220-F (104.5°C) and the burner operated. The device shall function to shut off the gas supply when the temperature of the stored water within the upper 6 in (152 mm) of the storage vessel Is at or below 21 0-F (99°C).
