Liquid Controls Mechanical Eliminators - Manual (Page 7)

7
Principles of design
dUal head bUlk PlanT aIr elIMInaTors
By employing two air eliminators, a high mount air
eliminator and a low mount air eliminator, dual head
bulk plant air eliminators save the metering system from
shocks incurred by recurring small slugs of air (or vapor)
and prevent large slugs of air from passing by the air
eliminator and through the meter system.
Each time a standard air eliminator removes a small
slug of air, it closes the downstream differential valve.
When the the differential valve closes at a high flowrate,
meter systems can incur a significant hydraulic shock.
Repeated shocks of this nature can shorten the life of
the metering system.
Dual head bulk plant air eliminators have a high mount
air eliminator that eliminate small slugs of air without
stopping the product flow through the meter system
to save the system from shock. Dual head bulk plant
air eliminators also have a low mount air eliminator to
remove large air slugs.
Occasionally, large slugs of air can overtake a
standard air eliminator, and excess air can blow by
the air eliminator and pass through the meter causing
inaccurate metering. With a dual head bulk plant air
eliminator and a differential valve as part of the metering
system, the float in the low mount air eliminator drops
in the presence of a large slugs of air, the differential
valve senses the presence of air as the pressure above
and below the diaphragm, and the valve closes until the
large slug of air is removed. When the float rises and the
valve opens, the high mount air eliminator removes the
remaining air in the vessel.
Dual head bulk plant
air eliminators require a
differential valve and they
can only be mounted in
fixed installations. They
are ideal for applications
when product is being
metered into storage from
a truck or transport with
a pump mounted on the
truck.
Single Head Bulk Plant Air Eliminator with Optical Sensor
InTrodUCTIon
Dual Head Bulk Plant Air Eliminator
sInGle head bUlk PlanT aIr elIMInaTor WITh
oPTICal sensor
The Single Head Bulk Plant Air Eliminator with Optical
Sensor performs the same functions as the Dual Head
Bulk Plant Air Eliminator. Both air eliminators use a
high mount air eliminator to siphon air without stopping
the flow. But instead of a low mount mechanical air
eliminator,
the Single Head Bulk Plant Air Eliminator
with Optical Sensor uses an optical sensor to identify
large air slugs. When the optical sensor identifies a
large air slug, it instantly signals an electronic preset or
register (Toptech’s MultiLoad presets or Liquid Controls’
LectroCount registers). The electronic device closes a
downstream control valve, stopping the product flow, and
the air slug is quickly vented.
The optical sensor provides several advantages over its
mechanical counterpart. The optical sensor’s reponse
time is much faster than pneumatic-based mechanical
air eliminators. The optical sensor has no moving parts
or piping requirements, which can simplify installation
and maintenance.