Howden Roots 2500 Series WHISPAIR MAX, Инструкция по установке, эксплуатации и обслуживанию

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ISRB
2005 GEA 20260
Page 18 of 24
DVJ Blowers are supplied with Internal Abradable Graphite-Based Coating
Coating
The coating is basically a fine-grained natural
graphite**. It is applied as several coats. Coating
applied after the machine’s internal clearances and
impeller timing are established. The effect of coating
is to close up internal clearances, decreasing slip and
increasing flow and efficiency at any given speed.
Exhaust air may carry some coating particles.
Characteristics of Machines with Coated Internal
Service
Machines with internal abradable coating are for use
with clean, dry air only.
After coating, it is not practical to try to measure
clearances involving these surfaces before or after
running the machine. After coating and before
running, some coated surfaces may even be
touching. After running, the coated surfaces may
have abraded areas and scratches, due to run-in
contact between the surfaces.
Do not attempt to measure clearances involving
coated surfaces as a basis for setting impellers in
relation to the cylinder bore, headplates, or each
other (fronts and backs).
Clearance settings can be made accurately only with
uncoated parts.
Cleaning and Preservation
Where internal, inspection indicates a need for
cleaning coated surfaces of dirt, dust, etc., wipe clean
only with a clean, dry rag. Do not use a solvent or
cleaner of any kind or allow a solvent or cleaner to
reach these surfaces while cleaning uncoated
surfaces.
If internal protection from rust or corrosion is required
due, for example, to removal of the machine from
service, or if the internal protections furnished as
shipped by the factory has been removed, do not use
a liquid preservative of any kind on these coated
surfaces. Bags of vapor inhibitor powder, such as
Shell Oil Company VPI No. 250 may be used
internally, with all machine openings sealed with
vapor barrier paper or tape.
Trouble Shooting Check List
This list in standard instructions applies, except note
that in those lists and in various locations throughout
the standard instruction manuals for uncoated
machines, rubbing, knocking, contact and wear
between internal surfaces are mentioned as trouble
indicators. This is with respect to metal-to-metal
interference. Coated surfaces can have very close
clearances and will wear in, or abrade, between
surfaces, showing rub or scratch marks which are
normal conditions. These can usually be
differentiated from metal-to-metal contact.
Cleaning, Coating & Curing Procedures for
Applying Abradable Coating
General. These procedures are for coating new
uncoated repair parts, spot repair of coating, or
renewal. If setting clearances and timing are
involved, this should be done before the new parts
are coated. Subsequent cleaning and coating may
involve at least partial disassembly for proper
cleaning without damaging the coating of other
original parts still coated, and to apply coating
properly.
Normally, for new uncoated surfaces, three coats are
applied and each coat must be properly cured.
Cleaning Before Coating
For new uncoated surfaces, apply the cleaner with a
clean, “soaked” rag. Apply the cleaner liberally, allow
to set for one to two minutes, then wipe off. Repeat if
necessary. Avoid cleaning surfaces which will not be
coated.
Wiping off with a clean, dry rag is the only cleaning
allowable for spot repair or renewal of existing
coating except in the case of a small area of grease
or similar substance where scraping clean before
reaching bare metal may be attempted. If too dirty to
clean by these methods, disassembly will be required
to remove the coating entirely, solvent clean, and
recoat.
Preparation of Coating Material
The graphite suspended in the material settles out in
a fairly short time and the can must be shaken well,
and also frequently, during spray application.
Generally, the initial shaking should continue until the
ball in the can rattles freely and should then continue
for at least five minutes more.
ISRB 2005 GEA 20260.indd 18 17/09/2015 12:53