Maintenance - Emerson Fisher ACE95 Series Instruction Manual

ACE95 Series
Shutdown
Installation arrangements vary, but in any installation
it is important to open and close valves slowly and to
close the upstream shutoff valve first when shutting
down the system.
Diagnostics
If a diagnostics pressure gauge was not
ordered with the unit, a pressure gauge
must be installed in the diagnostic port
to perform diagnostic analysis.
Diagnostics are an optional feature of the
ACE95 Series Tank Blanketing valves that aid in
evaluating valve operation. The diagnostic analysis
relies on the relationship of pilot pressure and pressure
in the main valve chambers (see Figure 3). The basic
relationships are as follows:
In order to evaluate a valve, examine the valve
nameplate to determine the C
range main valve spring. The inlet pressure gauge
indicates actual pressure supplied to the valve.
Follow these steps and refer to the diagnostics tables
on the following pages to evaluate a valve under
actual operating conditions:
1. Select the Table (Tables 3 through 8) that
corresponds to the C
your valve.
2. Determine the actual valve operating inlet pressure
in the first column of the diagnostics table.
Table 2. Diagnostic Analysis Pressure Ranges
DIAGNOSTIC
(PRESSURE CHAMBER)
Equal to inlet supply pressure
Slightly below inlet supply pressure
Well below inlet supply pressure
3. In the second column of the table, determine the
pressure of the pilot as it opens.
4. Determine the diagnostic pressure for the start to
open pressure of the main valve in the third column.
5. The fourth column displays the diagnostic
pressure for the full open pressure of the main valve.
Dow Corning is a mark owned by Dow Corning Corp.
®
Loctite ® is a mark owned by Henkel Corporation.
6
Note
and inlet pressure
v
and inlet pressure range of
v
STATUS
Pilot and main valves are closed.
Tank at or above set pressure.
Pilot valve supplies gas to tank.
Tank pressure is just below
set pressure.
Pilot and main valves are both
supplying gas to the tank. Tank
pressure is below setpoint.
There are four pressures involved in evaluating a
valve: actual inlet pressure, pressure to start opening
pilot valve, pressure to start opening main valve and
pressure to fully open main valve.
Actual Inlet Pressure: The gas pressure supplied
to the inlet of the valve. This is the maximum
diagnostic pressure.
Pressure to Start Opening Pilot Valve: The
diagnostic pressure drops to this value as the valve
senses decreasing tank pressure. The main valve
remains closed at this pressure.
Pressure to Start Opening Main Valve: The
diagnostic pressure drops to this level as the tank
pressure decreases and reaches the valve setpoint.
The pilot is fully open at this pressure.
Pressure to Fully Open Main Valve: At this point,
both the main valve and pilot valve are fully open and
supplying gas to the tank.

Maintenance

Valve parts are subject to normal wear and must be
inspected and replaced as necessary. The frequency
of inspection and replacement of parts depends on the
severity of service conditions and the requirements
of local, state, and federal regulations. Due to the
care Emerson takes in meeting all manufacturing
requirements, use only replacement parts
manufactured or furnished by Emerson.
All O-rings, gaskets, and seals should be lubricated
with a good grade of general purpose lubricant and
installed gently rather than forced into position.
Suggested lubricant, sealant, and adhesive are
as follows:
Lubricant: Dow Corning
Sealant: Loctite ® PST #592,
Polytetrafluoroethylene (PTFE) Tape or equivalent
Adhesive: Loctite ® #222 or equivalent
Be certain that nameplates are updated to accurately
indicate any field changes in equipment, materials,
service conditions, or pressure settings.
Monthly Maintenance
1. Visually inspect the unit to ensure tight connections,
tight seals, and safe operation.
2. Observe the blanketing pressure.
3. Inspect the inlet pressure for the proper pressure
range (stamped on the valve nameplate).
® 111 or equivalent