521 Series Inverted Bucket Steam Traps

521 Series Inverted Bucket Steam Traps
Forged Carbon Steel for Vertical and Horizontal Installation
Steam Trapping and
Steam Tracing Equipment
For Pressures to 1 000 psig (69 barg)...Capacities to 1 300 lb/hr (590 kg/hr)
521 Side Inlet, Side Outlet Traps
Add suffix “CV” to trap number for internal check valve.
Model No. Screwed
or SW Model No. Flanged
Model 521 Trap
Description
Armstrong Model 521 horizontal installation offer smaller capacities at higher pressures.
A unique leverage system multiplies the force provided by the bucket to open the valve against
system pressure. The mechanism is free-floating and has no fixed pivots to create wear or friction, because the mechanism is located at the top of the trap, no dirt can collect on the orifice.
Small particles of dirt are held in suspension until discharged by the full differential purging
action when the bucket sinks, pulling the valve off the seat. The discharge orifice is surrounded
by a water seal, preventing live steam loss. Automatic air venting is provided by a small vent
hole in the bucket. Inverted bucket traps drain continuously to prevent condensate backup.
They are also resistant to water hammer. Model 521 adds the convenience and savings of in-line
repairability and is designed to meet today’s energy-management requirements efficiently and
economically over a long, trouble-free service life.Model 521 have integral strainer to protect
from dirt and scale
521
521-FW
in
mm
Pipe Connections
1/2, 3/4
15, 20
“A” (Diameter)
“B” (Height, Screwed or SW)
8
10-5/16
203
263
“BB”
12-1/8*
308*
4
102
20
“G” (Body OD)
“K” (CL Outlet to CL Inlet)
Number of Bolts
8
Weight Scr. or SW lb (kg)
20(9.0)
Weight, Flanged lb (kg)
26(11.9)
Model 521 Capacity
*“BB” dimensions shown are for 3/4" conn., Class 900 flanged. Consult factory for
dimensions of models with other connection sizes and/or flanges.
Connections
Screwed NPT and BSPT
Socketweld
Flanged
See page 185 for dimensional information for flanged and socketweld connections.
Materials
Body: 521 Body:
521 Cap:
Internals: Valve and seat: Strainer Screen
Bolt/Nut
ASTM A105
ASTM A105N
ASTM A105N
All stainless steel—304
Titanium
Stainless Steel
ASTM A193 Gr B7 / ASTM A194 Gr 2H
Specifications
Inverted bucket steam trap, type ... in forged carbon steel, with continuous air venting at steam
temperature, free-floating stainless steel mechanism, with the discharge orifice at the top of the
trap.
How to Order
Specify:
• Model number
• Size and type of pipe connection. When flanges are required, specify type of flange in detail
• Maximum working pressure that will be encountered or orifice size
• Any options required
• Integral Screen Required
NOTE: #38 orifice in Model 521 is limited to 560 psig (39 barg).
Pressure-Temperature Rating for Forged Steel Traps
Model
No.
Max. Oper.
Pressure, Sat.
Steam
521
1 000 69
psig
barg
Maximum Allowable Pressure (Vessel Design) of
Pressure-Containing Parts at Indicated Temperature
°F
°C
-20/+650 -28/+343
psig
barg
1 000
69
°F
°C
°F
°C
399
°F
°C
700
371 750
800 427
psig
barg psig barg psig barg
1 000 69 950 65.5 840 58
NOTE: Maximum operating pressure to be marked on nameplate will be determined by
actual orifice used. Maximum allowable pressures shown in boldface will be marked on
nameplate, unless otherwise requested. Traps with flanges may have different pressuretemperature ratings.
1
Designs, materials, weights and performance ratings are approximate and subject to change without notice. Visit armstronginternational.com for up-to-date information.
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