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 296-307-41049 - Liquid-level gauging devices

Current through Register Vol. 24-14, July 15, 2024
(1)
				  Each container manufactured after December 31, 1965, and filled on a volumetric
				  basis must have a fixed liquid-level gauge to indicate the maximum permitted
				  filling level according to subsection (5) of this section. Each container
				  manufactured after December 31, 1969, must have permanently attached to the
				  container adjacent to the fixed level gauge a marking showing the percentage
				  full that will be shown by that gauge. When used with a variable liquid-level
				  gauge, the fixed liquid-level gauge will act as a check on the variable gauge.
				  Gauges must be used in charging containers as required in WAC
				  296-307-41034.
(2) All variable
				  gauging devices must be arranged so that the maximum liquid level for butane,
				  for a 50/50 mixture of butane and propane, and for propane, to which the
				  container may be charged, is easily determined. Liquid levels from empty to
				  full must be marked on the system nameplate or gauging device. Dials of
				  magnetic or rotary gauges must show whether they are for cylindrical or
				  spherical containers and whether for aboveground or underground service. The
				  dials of gauges for aboveground containers of over 1,200 gallons water capacity
				  must be so marked.
(3) Gauging
				  devices that require bleeding of the product to the atmosphere, such as the
				  rotary tube, fixed tube, and slip tube, must be designed so that the bleed
				  valve maximum opening is not larger than a No. 54 drill size, unless provided
				  with excess flow valve.
(4) Gauging
				  devices must have a design working pressure of at least 250 psig.
(5) Length of tube or position of fixed
				  liquid-level gauge must be designed to indicate the maximum level to which the
				  container may be filled for the product contained. This level must be based on
				  the volume of the product at 40°F at its maximum permitted filling density
				  for aboveground containers and at 50°F for underground containers. The
				  employer must calculate the filling point for which the fixed liquid level
				  gauge must be designed according to this section.
Note:
It is impossible to set out in a table the length
								of a fixed dip tube for various tank capacities because of the various tank
								diameters and lengths, and because the tank may be installed either vertically
								or horizontally. If the maximum permitted filling volume in gallons is known,
								however, the employer can determine the length of the fixed tube by using a
								strapping table from the container manufacturer.
The fixed tube should be long enough so that when
								its lower end touches the surface of the liquid in the container, the contents
								of the container will be the maximum permitted volume as determined by the
								following formula:
Click to view
								image
1 Measure at
								60°F.
2 From WAC
								296-307-41037(1).
3 For aboveground
								containers the liquid temperature is assumed to be 40°F and for underground
								containers the liquid temperature is assumed to be 50°F. To correct the
								liquid volumes at these temperatures to 60°F, use the following
								factors:
(a) To
				  determine maximum volume of LP-gas for which a fixed length of dip tube must be
				  set:
TABLE U-6
VOLUME CORRECTION FACTORS
Specific gravity
Aboveground
Underground
0.500
1. 033
1. 017
.510
1. 031
1. 016
.520
1. 029
1. 015
.530
1. 028
1. 014
.540
1. 026
1. 013
.550
1. 025
1. 013
.560
1. 024
1. 012
.570
1. 023
1. 011
.580
1. 021
1. 011
.590
1. 020
1. 010
(b) To calculate the maximum volume of LP-gas
				  that can be placed in a container when determining the length of the dip tube
				  expressed as a percentage of total water content of the container, use the
				  formula in (c) of this subsection.
(c) Determine the maximum weight of LP-gas
				  that may be placed in a container for determining the length of a fixed dip
				  tube by multiplying the maximum volume of LP-gas from Table U-6 by the pounds
				  of LP-gas in a gallon at 40°F for aboveground and at 50°F for
				  underground containers. Typical pounds per gallon are specified below:
Example:
Assume a one hundred gallon total water capacity tank
							 for aboveground storage of propane having a specific gravity of 0.510 of
							 60°F.
Click to view
					 image
Aboveground,
pounds per
gallon
Underground,
pounds per
gallon
Propane
4.37
4.31
N Butane
4.97
4.92