ord_163 - Laserfiche WebLink

Home

149 ORDINANCE No. 163 SECTION 3 -12 AUTOMATIC SAFE,]Y VALVE CONTROL Safety shut-off v:alves shall be tested to assure gas tightness of the seat when in the closed position; the valve assembly shall be gas tight in all positions. Packing glands shall be designed so that the valve will not be made inoperative by excessive tightening of the packing nut. Either the valve shall incorporate means for requiring a manual opera- tion for reopening of the valve after it has been -closed on the electrical circuit shall be so arnanged as to require a manual operation to re-open the valve after it has been closed. In no case shall valves be able to be opened manually until safety pilots are lighted and circuit completed or low-water cutoff circuit has been completed. SECTION 3- 12.1 Where a switch is installed in the low-water cutoff circuit to keep circuit to safety shut-off valve closed when blowing down water column, switch must be of the push button type so that when operator releases button the control circuit to safety shut-off valve will be normal. SECTION 3-12.2. On large boilers where a competent attendant is constantlT on duty, it will be permissible to install a bypass around the safety valve with the valve in the bypass locked or sealed. In large boiler plante using steam for generation of power or light and having competent operators on duty at all times, the use of limiting devices as covered in Paragraph 11 will not be mandatory. SECTION 3~13 COMBUSTION CONTROL: For burners or a combination of burners not exceeding a total input of 500,000 BTU per hour, a combustion control of the on-off type with-quick opening control valves may be used. SECTION 3-13.1 For a burner or a combination of burners not exceeding 2,500,000 BTU per hour input, an on-off type of control may be used provided the automatic . gas valve is of the slow opening type. Valve must be so designed that an adjustable opening time of from ten (10) to thirty (30) seconds may be obtained and with a closing time not to exceed five (5) seconds. SECTION .3-13.2 For a burner or a combination of burners with a total input exceeding 2,500,000 BTU per hour, a combustion control of the modulating type must be used. Where the uptake or outlet damper is securely locked in a fixed position for maximum load conditioR, the control may be of the type that operates the inlet air louvre of the burner in conjunction with the gas valve by means of mechanical linkage The control. may also be of the type that operates the uptake or outlet damper in conjunction with the. gas control valve or valves, either b,y mechanical