Installation And Startup - Fisher 1290 Instruction Manual

Type 1290
The Type 1290 vapor recovery regulator responds to
any changes in the blanket gas pressure and throttles
open or close to control the flow of the blanket gas out
of the vessel. A vacuum source on the outlet of the
regulator is necessary to ensure flow of low-pressure
blanket gas out of the vessel and into a vapor recovery
system. The higher the vacuum source, the more the
flow capacity of the vapor recovery regulator.
The pressure of the blanket gas registers under the
diaphragm of the pilot. A Type MR95H regulator provides
a constant loading pressure source to the Type EGR
main valve actuator. When the pilot is closed, the loading
pressure fills both sides of the Type 1098 actuator through
a fixed restriction.
The Type EGR main valve spring keeps the main
valve plug tightly shut. When the vessel blanket gas
pressure reaches the setting of the pilot spring, the
pilot diaphragm moves, opening the pilot valve disk
and exhausting some of the Type 1098 actuator's
loading pressure through the pilot orifice. This typically
happens when the vessel is being filled with liquid.
The small fixed restriction maintains a higher loading
pressure on the bottom of the Type 1098 actuator. The
pressure differential across the main valve diaphragm
moves the diaphragm upward causing the main valve
to open which allows the blanket gas to flow out to
the vapor recovery system vacuum source, hence
controlling the vessel blanket pressure.
When the vessel blanket gas pressure begins to
stabilize, the pilot spring throttles and the pilot disk
closes. This allows the loading pressure source to fill
both sides of the Type 1098 actuator through the fixed
restriction. This equalizes the pressure acting on the
diaphragm, thus allowing the main valve spring to close
the main valve plug.

Installation and Startup

!
Personal injury, equipment damage or
leakage due to escaping accumulated
gas or bursting of pressure-containing
parts may result if this gas blanketing
system is overpressured or installed
where service conditions could exceed
the limits given in the Specifications
section and on the appropriate
nameplate, or where conditions exceed
any ratings of the adjacent piping or
piping connections.
4
WARNING
To avoid such injury or damage, provide
pressure-relieving or pressure-limiting
devices (as required by Title 49, Part 192,
of the U.S. Code of Federal Regulations,
by the National Fuel Gas Code Title 54 of
the National Fire Codes of the National
Fire Protection Association or by other
applicable codes) to prevent service
conditions from exceeding those limits.
Additionally, physical damage to the
vapor recovery regulator system could
result in personal injury and property
damage due to escaping accumulated
gas. To avoid such injury and damage,
install the vapor recovery system in a
safe location.
CAUTION
On the Type EGR main valve, normal
pressure drop assists shutoff, therefore,
leakage may result during any reverse
pressure drop condition.
1. Call qualified personnel when installing, operating and
maintaining regulators.
2. Before installing, inspect the main valve, pilot and
tubing for any shipment damage or foreign material
that may have collected during crating and shipment.
Make certain that the body interior is clean and the
pipelines are free of foreign material.
3. Apply pipe compound only to the external pipe threads
with a threaded body, or use suitable line gaskets and
good bolting practices with a flanged body.
4. The Type 1290 vapor recovery regulator should be
installed as shown in Figure 1 so that flow through the
Type EGR main valve matches the flow arrow attached
to the valve body.
WARNING
!
A regulator may vent some gas to
the atmosphere. In hazardous or
flammable gas service, vented gas may
accumulate and cause personal injury,
death or property damage due to fire or
explosion. Vent a regulator in hazardous
gas service to a remote, safe location
away from air intakes or any hazardous
location. The vent line or stack opening
must be protected against condensation
or clogging.