have multiple areas designated within
each plant with different approval
requirements depending on the media
that could or would be present in those
areas of the plant. These decisions have
to be made when the plant is designed,
and they are reviewed by the appropriate safety officials and insurance companies. However, hazardous environment considerations are an area of
major expense for end users and for
solenoid manufacturers. The initial cost
to get approvals is just the beginning of
that cost. Next come regular plant
inspections, file fees and paperwork
change charges.
VOLTAGE
Voltage is a simple, but still vital part of
the specification process. It merely is the
voltage of the system to which the valve
is wired. Most coils are designed per UL
requirements to operate at +10% to -
15% of the rated voltage because of normal voltage fluctuations in the line or
from the source. However, care is needed
with voltage range tolerances, because
all coils are not designed this way. The
information needed to determine coil
A solenoid valve manifold is used for fluid
power and process valve automation
applications. One manifold can contain
several 3- and 4-way solenoid valves together.
design is in the valve manufacturer’s
installation and maintenance sheets or
catalog information. When specifying
voltage do not assume that the manufacturer knows whether voltage requirements are AC or DC. When specifying
DC voltage, the letters DC should be
written out after the voltage value: as in
24/DC. When specifying AC voltage, the
frequency should be included (For example: 120/60 or 230/50).
EXTRAS
The extras category in specification
points can mean just about anything. For
example, if something like extra-long
lead wires, manual operator, mounting
bracket, manual reset, functional safety
data, certificates of compliance, low
power or bus system compatibility is
added, it can be mentioned under
“extras.” Many extra features are possi-
ble, but not always available on every
solenoid valve. Those specifying solenoid
valves need to use this category to list
what’s not listed in the other categories.
BILL REESON is a technical support manager at
Emerson Industrial Automation, ASCO Numatics
( www.ASCONumatics.com). Reach him at
Bill.Reeson@Emerson.com.
