Taylor-Wharton Bulk Tank Safety Data - Manual (Page 12)

Pressure Building Circuit
The pressure building system provides a means of maintaining tank
pressure at a preset value during product withdrawal. This system
operates when the pressure building isolation valves are opened. Liquid
flows through the pressure regulator to the pressure building vaporizer.
The resulting gas flows to the top of the liquid container, increasing tank
pressure. When the pressure reaches the setting of the regulator, it closes
to prevent further flow of liquid into the systems. When product with-
drawal lowers tank pressure below the regulator setting, more liquid ill be
vaporized to maintain tank pressure for continue withdrawal.
Product Withdrawal
Product is normally withdrawn as liquid through a liquid withdrawal line.
Liquid flows through the withdrawal valve to an external vaporizer. When
the pressure building valves are open and tank pressure exceeds the
setting of the economizer valve, gas will flow from the top of the tank
through the pressure building system and the economizer valve to the
liquid withdrawal line. This action interrupts the flow of liquid, allowing gas
to flow through the withdrawal line until tank pressure falls below the
setting of the economizer valve. This economizer action reduces product
losses by allowing the withdrawal of gas that may otherwise be vented.
Safety Devices
Overpressure protection for the liquid container is provided by pressure
relief devices consisting of safety valve and a bursting disk. An optional
Dual Safety Relief Manifold with a three-way diverter valve permits the
operation of one set of protective devices while the other set is isolated for
maintenance. This arrangement prevents all safety devices from being
valved out of the circuit at the same time and permits maintenance of
these devices without the need to blow-don tank pressure.
The inner container and plumbing of all Taylor-Wharton tanks have been
“Cleaned for Oxygen or Hydrogen Service” (specification GS38 or GS40
respectively. You should take appropriate measures to assure that only
clean liquid, free of particulate matter, be placed in your container.
Warning
Once a container is placed into Carbon Dioxide or Nitrous Oxide
gas service, it should never be placed into any other gas service
.
12
Initial Filling Safety