3.3.4
Operating a Dispenser to Fill DOT
Cylinders by Volume
DOT cylinders are designed to be transported filled to
their maximum permitted filling limits. NFPA 58, LP-Gas
Code, states that large DOT cylinders having water
capacities of 200 pounds or more may be filled by volume.
In this module you will learn to identify:
(1) NFPA code requirements for filling cylinders by volume
(2) Volumetric filling procedures that apply to dispenser
transfer operations
3.3.4 Student Book  © 2004 Propane Education & Research Council
Page 1
NFPA Code Requirements for Volumetric Filling
NFPA 58
2001
4.4.3.2 The volumetric method shall be limited to the
following containers, where they are designed and
equipped for filling by volume:
(1) Cylinders of less than 200-lb water capacity that are not subject to
DOT jurisdiction
(2) Cylinders of 200-lb water capacity or more
NFPA 58
7.4.3.1 (1) & (2)
2004
3.3.4 Student Book  © 2004 Propane Education & Research Council
Page 1
NFPA Code Requirements for Volumetric Filling
Three points should be understood concerning 4.4.3.2:
1.
DOT cylinders must have properly operating fixed maximum liquid
level gauges and correct length dip tubes before they can be filled
by volume.
2.
Provision (1) of 4.4.3.2 means that DOT cylinders of less than 200
pounds water capacity transported in commerce (subject to DOT
jurisdiction) must be filled by weight. (See footnote) A DOT motor
fuel cylinder used on forklift operated only within the bulk plant can
be filled by volume, because it will not be transported in commerce.
Similarly, motor fuel cylinders filled at a dispenser at commercial
customer locations may be filled by volume, if the cylinders are not
transported off-site.
3.3.4 Student Book  © 2004 Propane Education & Research Council
Page 1
NFPA Code Requirements for Volumetric Filling
Three points should be understood concerning 4.4.3.2:
3.
Provision (2) of 4.4.3.2 means that large
cylinders (in excess of 200 pounds)
designed for stationary installation may
be filled by volume at any location.
Figure 1. Stationary DOT Cylinder
3.3.4 Student Book  © 2004 Propane Education & Research Council
Page 2
Procedures for Volumetric Filling
Step 1:
Complete an external visual inspection of the cylinder. If any
defect is found that requires the cylinder to be condemned,
removed from service, or if the cylinder requalification
marking is not current—stop and do not continue the filling
operation.
Step 2:
Open the liquid outlet valve on the dispenser storage tank
and the valve in the by-pass return line.
Step 3:
Open the vent valve on the fixed maximum liquid level
gauge. If liquid (steady white mist or fog) appears and
continues to vent after a few seconds—stop and do not
continue the filling operation—the cylinder is already filled. If
no liquid appears, or immediately disappears after initial
venting, continue the filling operation.
3.3.4 Student Book  © 2004 Propane Education & Research Council
Pages 2 & 3
Procedures for Volumetric Filling
Step 4:
Using the required adapter, connect the transfer hose to the
cylinder fill valve or service valve outlet or coupling.
Step 5:
Start the pump.
Step 6:
Open the valve slowly on the end of the hose.
Step 7:
If applicable, open the service valve slowly on the cylinder.
Step 8:
When a steady white mist fog is first emitted from the gauge
vent valve, this indicates the maximum permissible fill level
has been reached. Immediately close the hose end valve.
Step 9:
Close the fixed maximum liquid level gauge.
3.3.4 Student Book  © 2004 Propane Education & Research Council
Pages 2 & 3
Procedures for Volumetric Filling
Step 10:
Shut off the pump.
Step 11:
Close the cylinder service valve, if applicable.
Step 12:
Partially disconnect the filling adapter (approximately ¼ turn)
until all trapped liquid is vented. If liquid venting through a fill
valve does not stop within seconds, retighten and seal the
filling adapter. Allow a few seconds for the vented propane
to disperse. Use a rubber or plastic mallet to strike the filler
valve to re-seat its back checks, then partially disconnect
again to vent the trapped propane.
Step 13:
After the trapped propane has vented, disconnect the
transfer hose and secure it in its holder or stowed position.
3.3.4 Student Book  © 2004 Propane Education & Research Council
Page 3
Procedures for Volumetric Filling
Step 14:
Check the cylinder and its valves for leaks. Check to ensure
the cylinder is not overfilled.
Step 15:
Apply DOT labels or a cylinder warning label if the original
manufacturer’s label is not legible.
3.3.4 Student Book  © 2004 Propane Education & Research Council
Page 3
Time to See If You Got the Key Points of
This Module…
• Complete the Review on page 4.
• See if you are ready for the Certification
Exam by checking off the
performance criteria on page 5.
3.3.4 Student Book  © 2004 Propane Education & Research Council
Pages 4 & 5