Dispense Requests And Valves Overview - Graco HFRL Setup And Operation Manual

Dispense Requests and Valves Overview

Dispense Requests and
Valves Overview
Three types of dispense valves can be used with the
HFR system:
• Stall-at-pressure
• Solenoid controlled
• Hydraulically actuated and recirculating
The P2 Gun and Fusion Gun are examples of
stall-at-pressure dispense valves. When not dispens-
ing, the fluid in the chemical lines are fully pressurized.
When using a stall-to-pressure dispense valve, a
footswitch cannot be used. Any signals sent from a
footswitch will be ignored. In this configuration, the user
is responsible for supplying voltage to any solenoid
used to control the opening or closing of the dispense
valve. The output from the HFR used to control a valve
solenoid must be disconnected.
The EP Gun and MD2 Valve are examples of solenoid
controlled dispense valves, which are controlled by the
HFR. The user does NOT directly control the dispense
valve solenoid. In this configuration, the user requests a
dispense either by using the ADM dispense key, or by
supplying a contact closure input at the footswitch
input to the HFR. When the machine sees the signal,
the dispense will start and the HFR will source power to
the dispense valve solenoid. When the dispense
request trigger is released, the HFR will remove power
to the dispense valve solenoid and pressurize the lines
to the pressure monitored during the dispense.
The L-Head, S-Head, and GX-16 are examples of
hydraulically actuated, full recirculating dispense
valves. When not dispensing, material is recirculated to
maintain temperature and pressure. Opening and clos-
ing the valve is controlled hydraulically, which leads to
faster actuation and more accurate dispenses.
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