BNP PRESSURE BLAST CONVERSION KIT Page 3
Excessive air pressure could cause the blast
machine to rupture. To prevent serious injury or
death, do not exceed the rated pressure of the
blast machine vessel.
1.5.4 OSHA does not require pressure relief valves
on blast machines when air compressors supplying air to
the blast machines are built to ASME
(1)
specifications
and comply with OSHA
(2)
regulations. ASME Manual
section VIII, Division 1, UG-125, paragraph A90 (g)
states that pressure relief valves or protective devices
"...need not be installed directly on a pressure
vessel when the source of pressure is external to the
vessel and is under such positive control that the
pressure in the vessel cannot exceed the maximum
allowable working pressure at the operating
temperature...". OSHA regulation 1910.169 refers to
the above ASME code when describing the necessity of
pressure relief valves on compressed air equipment. DO
NOT operate blast machines with air compressors that
are not equipped with properly functioning pressure relief
valves.
(1)
American Society of Mechanical Engineers, Boiler and Pressure
Vessel Code, 1989
(2)
Occupational Safety and Health Administration, 29 CFR 1910,
Subpart M - Compressed Gas and Compressed Air Equipment.
1.5.5 When the air supply is on, and the cabinet doors
are closed, the blast machine is ready for actuation by
the foot pedal. Pressing the foot pedal opens the
normally closed main inlet regulator, and closes the
normally open outlet valve. The incoming air pressurizes
the blast machine, and blasting begins. When pressure
on the foot pedal is released, the blast machine
depressurizes, and blasting stops.
1.6 Nozzle Options
1.6.1 Unless specified at the time of order, machines
are shipped with a 3/16" nozzle. Optional 1/8" nozzles are
available for use with all machines, and 1/4" nozzles are
for use with 900 cfm reclaimers only.
1.6.2 Use boron carbide nozzles when blasting with
aggressive media. See Optional Accessories, Section
9.1
1.7 Metering Valve Options
1.7.1 Unless specified at the time of order, machines
are shipped with a fine-mesh Sentinel metering valve. The
valve is for use with 50 mesh and finer media, and #10
and finer glass bead. The optional Sentinel metering valve
is for use with 50-mesh and coarser media. Conversions
kits easily convert the valves either way. Kits are listed
under Optional Accessories in Section 9.1.
1.8 Media
1.8.1 When the cabinet is adequately sized for the blast
machine and reclaimer, the machine utilizes most
common reusable media 25 mesh and finer (with the
appropriate metering valve) that is specifically
manufactured for dry blasting. The usable media size
range depends on the cabinet inlet dust and outlet size,
nozzle orifice size, media metering valve, and reclaimer
cleaning rate. Several factors affecting the reclaimer
cleaning rate include: air pressure, media/air mixture,
media friability, contamination of parts being cleaned,
and humidity. Media sizes shown under the media
headings are guidelines only, based on standard 3/16
orifice nozzle and average conditions.
As a rule, larger nozzles deliver more media, thus
demand higher reclaimer cleaning rates. With larger
nozzles, the maximum size of media decreases from
those recommended. Media finer than those
recommended may decrease visibility, and increase
carryover to the dust collector. Using media in the 200
mesh and finer range will usually require the addition of
the optional, externally adjustable vortex cylinder. See
Section 5.4. The vortex cylinder is standard on pull-
through systems (with reverse-pulse dust collectors).
Media coarser than those recommended may be too
dense for the reclaimer to recover from the cabinet
hopper.
1.8.2 Steel: Steel shot finer than 170 mesh and steel
grit finer than 40 mesh may be used with 900 cfm
reclaimers. Steel grit or shot should not be used with 600
cfm reclaimers. Conveying hose on cabinets using steel
media should be reduced and have a smooth durable
lining. Rubber curtains should be used to protect the
cabinet walls from peening and rapid wear.
1.8.3 Sand and Slag: Sand should never be used
because of the hazards of using media containing free
silica. Slags are not recommended because they rapidly
breakdown.
1.8.4 Aggressive media: Aluminum Oxide, Silicon
Carbide, Garnet, and abrasive such as these may be
used but consideration must be given to accelerated
wear on any part of the cabinet, reclaimer, nozzle and
hoses, which comes in contact with the media. If
aggressive media is used periodically, use an optional
aluminum oxide kit. When these media are used
extensively, use a fully rubber lined reclaimer, RP dust
collector, and boron carbide nozzles.
WARNING
To Next Page
Loading...
Need help?
General
