15
6.7 restricted lift valves
Crosby JOS-E and JlT-JOS- E pressure relief
valves are available in a restricted lift version�
all J series variations including JBS and all
service medias may be supplied in a restricted
lift version� The purpose of a restricted lift valve
is to more closely match the required capacity
of the protected vessel or pipe with the actual
and rated capacities of the relief valve providing
over-pressure protection�
Restricted lift (Rl) versions of the J series may
be built by a certified Emerson manufacturing
facility or by an aSME certified assembler with
the required certification specific to the Rl
version (National Board certificates 01045 and
01382)� any aSME marked Rl valve may be VR
repaired by a repair organization certified under
the National Board VR repair program� Existing
non- restricted lift versions of the J series may
be converted to the restricted lift version by
VR certificate holders� In addition existing Rl
versions may have their lift modified using the
same procedures�
noTe
Restricted lift valves may be identified by the restricted
lift nameplate by model number with “-Rl"�
6.7.1
Restricted lift valves have a limit spacer
that prevents the disc and disc holder
from lifting its limits� These valves may be
restricted to a minimum lift of 30% of the
full rated capacity or �080˝ (2�03 mm)�It is
important to check lift on all restricted lift
valves to ensure accuracy of the capacity
on the nameplate� For production
purposes the spacers are precut for 10%
increments� 5% increments can be added
for K orifice and larger�
6.7.2 Determining the correct limit spacer height
• The nameplate capacity should
be as specified on the nameplate
or determined by calculation
(See example on page 18)�
• The required lift should also
be specified on the nameplate
or determined by calculation
(See example on page 18)�
• Select the limit spacer(s) to the
required limit spacer height
(See Table 10 and 11)�
6.7.3 Measure the valve lift.
• Install the limit spacer (see Figure 13)
with the chamfer down and reassemble
the valve as described in Steps 6�6�1
through 6�6�10�
note:
install bellows to disc holder for
JBS F orifice valve, then install spacer�
• Measure the lift of the valve and
compare it with the required lift as given
on the restricted lift nameplate with
tolerance (�020”, +0�020” [-0�50 mm,
+0�50 mm])�
• Based on the results, if the lift is not in
the tolerance:
If the actual lift is less than required, machine
the limit spacer as necessary to obtain the
required lift� (Machine chamfer, deburr and
polish before installation into the valve�)
If the actual lift is greater than required, obtain
a new next taller limit spacer, and return to
section 13�3�1� (Machine chamfer, deburr and
polish before installation into valve�)
• Once correct lift is obtained,
disassemble the valve�
• Ensure the limit spacer has been
chamfered to fit over the radius of the
disc holder� The limit spacer must be
installed so that the chamfered end is
mating to the back face of disc holder,
and not sitting on the disc holder radius�
• Prior assembly, verify the lift for each
valve�
FIguRE 13
Restricted lift spacer
CauTion
Do not interchange internal parts or use a
different nozzle after a set of parts has been
custom-fit.
6.7.4 Assembly
Valves need to be assembled as per
section 6�6�
6.7.5 Restricted Lift Nameplate
For new restricted lift version valves, use
the restricted lift nameplate (See Figure 2�)
If a non-restricted lift J series PRV is
converted to the Rl version, or if the
restricted lift is changed on an existing
Rl version valve the following procedure
regarding nameplates should be followed�
• The information on the original ASME
nameplate which is changed by the
conversion, such as model number,
capacity and restricted lift should be
lightly etched out�
• Information changed by conversion of
the valve or change to the restricted
lift shall be included on the repair
nameplate to serve as a record of
the conversion and its effect on the
performance of the PRV�
Crosby
STylE JOS-E, JBS-E, JlT*-JBS-E, JlT*-JOS-E ValVES
InstallatIon and MaIntenance InstructIons
lift
restricting
spacer
