Pneumatic equipment should be maintained only by persons trained and
experienced in the maintenance of such equipment.
Supply Clean Air.
Foreign material lodging in valves is a major cause of breakdowns.
The use of a 5-micron-rated air filter located close to the valve is strongly recommended.
The filter bowl should be drained regularly, and if its location makes draining difficult,
the filter should be equipped with an automatic drain.
Check Lubricator Supply Rate.
A lubricator should put a fine oil mist into the
air line in direct proportion to the rate of air flow. Excessive lubrication can cause
puddling in the valve and lead to malfunctions. For most applications an oil flow
rate in the lubricator of one drop per minute is adequate.
Note that the double valve
itself does not require air line lubrication.
Compatible Lubricants.
Although this valve does not require air line lubrication,
it may be used with lubricated air being supplied to other mechanisms. Some oils
contain additives that can harm seals or other valve components and so cause the
valve to malfunction. Avoid oils with phosphate additives (e.g., zinc dithiophosphate)
and diester oils; both types can harm valve components. The best oils to use are
generally petroleum base oils with oxidation inhibitors, an aniline point between
180°F (82°C) and 220°F (104°C), and an ISO 32 or lighter viscosity.
Some compatible oils are listed above at the right. These oils, although believed
to be compatible, could change without notice because manufacturers sometimes
reformulate their oils. Therefore, use oils specifically compounded for air line service.
If it is a synthetic oil, contact the oil manufacturer for compatibility information.
Cleaning the Valve.
If the air supplied to the valve has not been well filtered, the
interior of the valve may accumulate dirt and varnish which can affect the valve's
performance. A schedule should be established for cleaning all valves, the frequency
depending on the cleanliness of the air being supplied.
VALVE MAINTENANCE
COMPATIBLE LUBRICANTS
Maker
Brand Name
Amoco .................. American Industrial Oil 32
............................. Amoco Spindle Oil C, Amolite 32
Citgo .................... Pacemaker 32
Exxon ................... Spinesstic 22, Teresstic 32
Mobil ..................... Velocite 10
Non-Fluid Oil ........ Air Lube 10H/NR
Shell ..................... Turbo T32
Sun ....................... Sunvis 11, Sunvis 722
Texaco .................. Regal R&O 32
Union .................... Union Turbine Oil
2
ROSS
CONTROLS
®
When and why does the valve require a reset signal?
The valve will only require a reset when the valve has detected asynchronous
movement of the two independent internal elements. This condition will be
indicated by a fault signal from the Status Indicator and an audible leak from
the silencer. For solenoid reset models, reset is accomplished by applying
a momentary signal to the reset solenoid. For air reset models, reset is
accomplished by applying a momentary air signal to the reset port. The
DM
2®
Series D double valves have an anti-tie-down feature that requires
both main valve solenoids to be de-energized while resetting.
Why will my valve not reset?
There are a few common conditions that can prevent reset from occurring.
1. If the main valve solenoids are energized the valve will not reset. This is a
safety feature of the DM
2®
Series double valves that prevents unintended
pressure output from occurring upon valve reset. There should be at least
a 200 ms delay between removing power from the reset solenoid and
applying power to the main valve solenoids.
2. If the pneumatic supply to port 1 is not sufficient the valve will not reset.
This is not unusual for initial testing and startup if full plant pressure and
volume is not applied and quick connects or small hoses are used.
3. If the supply pressure was removed before de-energizing the valve it
is possible that both valve elements are in the faulted condition. This
condition results in a greater leakage rate to the exhaust port when the
supply is reapplied, and increases the insufficient supply issue mentioned
in item #2.
4. The reset solenoid may be mounted backwards. In this case energizing the
reset solenoid will result in the release of air through the reset solenoid’s
exhaust port (through the nut mounted on the stem of the solenoid) and
no reset action can occur.
DM
2®
Operation Timing Chart
Outlet
Pressurized
Reset
Signal
Main
Solenoids
Supply
Pressure
Applied
1. Operating signal to main solenoids should be dual
channel, concurrent operation. Discordance of signals
should be less than 25 msec.
2. Turning off supply pressure while valve is energized
will result in a fault and then valve must be reset.
3. Fault detection is constant.
VALVE RESET INFORMATION
DM
2®
Reset Timing Chart
Outlet
Pressurized
Reset
Signal
Main
Solenoids
Supply
Pressure
Applied
1. Reset anti-tie-down feature requires main solenoids to be off
during reset.
2. Reset duration is momentary - 200 msec. min. recommended.
3. At end of reset signal, time is required for pilot chambers to
refill before operation - 200 msec. recommended.
4. Fault detection is constant.
5. Turning off supply pressure while valve is energized will result
in a fault and then valve must be reset.
To clean the valve, use any good commercial solvent. Do
not
scrape varnished surfaces. Also, do not use chlorinated solvents
or abrasive materials. The former damages seals, and abrasives
can do permanent damage to metal parts. Before reassembling
the valve, lubricate all sliding surfaces with a grease such as Dow
Corning BR 2 Plus.
Electrical Contacts.
In the electrical circuits associated with
the valve solenoids, keep all switches or relay contacts in good
condition to avoid solenoid malfunctions.
Replace Worn Components.
In most cases it is not necessary
to remove the valve from its installation for servicing. However,
turn off the electrical power to the valve, shut off the air supply,
exhaust the air in the system, and lock-out before beginning any
disassembly operation. Service kits are listed on page 3.
If you have any questions about installing or servicing your valve, call ROSS
Technical Services
at your nearest
ROSS location (see page 4) or in the U.S.A. at:
1-888-TEK-ROSS(835-7677)
.
