Washington Administrative Code › Title 296 - Labor and Industries, Department of › Chapter 296-307 - Safety standards for agriculture › SPECIALIZED OPERATIONS › Part U-2 - Hazardous Materials - Liquified Petroleum Gas › Section 296-307-41025 - Safety devices

Current through Register Vol. 24-14, July 15, 2024
(1)
				  Every container except those constructed according to DOT specifications and
				  every vaporizer (except motor fuel vaporizers and vaporizers described in WAC
				  296-307-41029(3) and
				  296-307-42007(6)(a)
				 whether heated by artificial means or not, must have one or more safety-relief
				  valves of spring-loaded or equivalent type. These valves must be arranged to
				  afford free vent to the outer air with discharge not less than five feet
				  horizontally away from any opening into the building that is below such
				  discharge. The rate of discharge must be according to the requirements of
				  subsection (2) or (4) of this section.
(2) Minimum required rate of discharge in
				  cubic feet per minute of air at one hundred twenty percent of the maximum
				  permitted start to discharge pressure for safety-relief valves to be used on
				  containers other than those constructed according to DOT specification must be
				  as follows:
Surface area sq. ft.
Flow
rate
CFM
air
Surface area sq. ft.
Flow rate CFM air
Surface area sq. ft.
Flow
rate
CFM
air
20 or less
626
170
3,620
550
9,470
25
751
175
3,700
600
10,170
30
872
180
3,790
650
10,860
35
990
185
3,880
700
11,550
40
1,100
190
3,960
750
12,220
45
1,220
195
4,050
850
13,540
50
1,330
200
4,130
900
14,190
55
1,430
210
4,300
950
14,830
60
1,540
220
4,470
1,000
15,470
65
1,640
230
4,630
1,050
16,100
70
1,750
240
4,800
1,100
16,720
75
1,850
250
4,960
1,150
17,350
80
1,950
260
5,130
1,200
17,960
85
2,050
270
5,290
1,250
18,570
90
2,150
280
5,450
1,300
19,180
95
2,240
290
5,610
1,350
19,780
100
2,340
300
5,760
1,400
20,380
105
2,440
310
5,920
1,450
20,980
110
2,530
320
6,080
1,500
21,570
115
2,630
330
6,230
1,550
22,160
120
2,720
340
6,390
1,600
22,740
125
2,810
350
6,540
1,650
23,320
130
2,900
360
6,690
1,700
23,900
135
2,990
370
6,840
1,750
24,470
140
3,080
380
7,000
1,800
25,050
145
3,170
390
7,150
1,850
25,620
150
3,260
400
7,300
1,900
26,180
155
3,350
450
8,040
1,950
26,750
160
3,440
500
8,760
2,000
27,310
165
3,530
Surface area = total outside surface area of container in
					 square feet.
(3) When the
				  surface area is not stamped on the name plate or when the marking is not
				  legible, calculate the area with one of the following formulas:
(a) Hemispherical heads: Area = (equals)
				  (overall length) X (outside diameter) X 3.1416.
(b) Other than hemispherical heads: Area =
				  (equals) (overall length) + 0.3 (outside diameter) X (outside diameter) X
				  3.1416.
Note:
This formula is not exact, but will give results
							 within the limits of practical accuracy for the sole purpose of sizing relief
							 valves.
(c) Spherical container: Area = (equals)
				  (outside diameter)2 X 3.1416.
(d) Flow rate: CFM air = (equals) required
				  flow capacity in cubic feet per minute of air at standard conditions, 60°F
				  and atmospheric pressure (14.7 psia).
For containers with total outside surface area greater than
					 2,000 sq. ft., the formula is: Flow rate CFM air = (equals) 53.632 A0.82 where
					 A = (equals) outside surface area of the container in square feet.
Valves not marked "air" have flow rate marking in cubic
					 feet per minute of LP-gas. These can be converted to ratings in cubic feet per
					 minute of air by multiplying the LP-gas ratings by factors listed below. Air
					 flow ratings can be converted to ratings in cubic feet per minute of LP-gas by
					 dividing the air ratings by the factors listed below.
AIR CONVERSION FACTORS
Container type
100
125
150
175
200
Air conversion factor
1. 162
1. 142
1. 113
1. 078
1. 010