1.
End Cap
is used as a flow control adjustment. Turn the end cap counterclockwise to increase
material flow rate.
2.
Air Cylinder
– This design utilizes a single acting spring return air cylinder.
3.
Air Inlet
– The fitting supplied is a collet type fitting which accepts a 4mm tube.
4.
Valve Body
– Stainless steel construction.
5.
Needle Retaining Cap
– Captures the dispense needle and positions the dispense needle
cannula against the valve shut off needle.
6.
Dispense Tip
– The Micro Needle Valve is specifically designed to use Loctite
®
stainless steel
cannula needles.
7.
Valve needle rod Shut-Off
– Stainless steel construction
8.
Luer Adapter
– Accepts Loctite
®
stainless steel cannula needles.
9.
Fluid Inlet
– Two fittings are supplied: 1/8" NPT x Luer connector and 1/8" NPT x 1/4" tube
10.
Bracket and Screw
- Optional hardware PN 985281.
2.2 Theory of Operation (refer to Figure 2)
The Micro Needle Valve is a pneumatically operated, normally closed, adjustable opening, needle
and seat valve which is designed to be used in conjunction with a pressure-time dispense system.
A pressure-time dispense system is made up of a controller/timer, a dispense valve, and a
pressure reservoir. The controller directs pressurized air to the actuator of the valve through the
inlet air port (1) for a pre-determined period of time. The resulting action is to retract the needle
rod assembly (2) from the seat inside the dispensing tip (3) allowing material to flow from the
material inlet (4) to the dispensing tip (5). At the end of the cycle the controller relieves the input
air pressure which allows the spring (6) to return the needle rod back to its position to close the
material path.
The Micro Needle Valve is capable of interfacing with pressure reservoirs or syringe barrels. When
using a pressure reservoir the adhesive is placed into a reservoir and a feed tube passes through
the lid of the reservoir into the adhesive bottle. The other end of the feed tube is connected to the
material inlet port of the dispense valve. When the reservoir is pressurized the adhesive flows into
the valve. The higher the pressure the greater the flow rate. The adhesive contacts the
pressurized air thus making the air quality a critical component of the system. Loctite recommends
filtered dry air for each system.
Many of the Loctite
®
UV curing adhesive products are packaged in 30 ml syringe barrels. The
Micro Needle Valve is delivered with a luer type of fitting to accommodate syringe barrels. The
syringe barrel attaches directly to the Luer fitting and acts as a pressure reservoir. An airline
adapter is attached to the syringe barrel and should be connected to a filter regulator, which
delivers pressurized air to the syringe barrel. The pressurized air forces the adhesive directly into
the dispense valve.
The pressure and the time settings are the two predominate variables controlling the amount of
adhesive that is dispensed from the valve. Secondary variables are the flow control adjustment
which regulates the distance the needle rod travels and the orifice size of the dispense tip. When
determining a suitable dispense dose it is advised to set a pressure and vary the time until the
proper dose is achieved. If the time setting is too great, increase product pressure, this will allow
for a shorter time element to obtain the same dose.
2. Description (continued)
3
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