Pouring - EQUIPMENT for polyurethane foam roofing

To run a PUF pouring process, one must solve the following technical problems:

• High-quality mixing of components
• Achieving a tough even jet at the mixer outlet
• Sufficient output rate of the unit
• High-quality washing (cleaning) of all ducts

The problems of quality component mixing and achieving an even jet should be considered as interrelated. Two component mixing techniques can be used in the polyurethane foam pouring process.

High Pressure Chamber Mixing

Components A and B are mixed in a dedicated high pressure chamber at 5 to 20 MPa (50 to 200 kg/cm2). This technique is considered to guarantee the best possible quality of component mixing and, consequently, the highest possible quality of the resulting plastic foam.

Mechanical Mixing in a Low Pressure Chamber.

Components A and B are continuously and separately fed into the common chamber, in which the agitator rotates, pass through the mixing area and move out together. A low pressure in the chamber provides a way to produce equipment which is less complicated in terms of technology and process, small-sized, portable, and several times cheaper than the big high-pressure pouring machines. However, such units have a limited output rate (max. 30 liters/min) and a short deviation-free horizontal jet range.

NST has developed and commercialized a variety of low-pressure PU foam pouring equipment with output rates varying from 2 to 6 L/min and from 8 to 24 L/min. The performance characteristics of our models are identical to those of their foreign counterparts, the only difference being the price.

NST Low Pressure Pouring Heads

Professional POURING equipment is complicated stationary high-pressure (or sometimes low-pressure) machines. These packages require time-consuming installation, special operating conditions, and dedicated maintenance. In fact, such equipment constitutes the main unit in a small or large-size production plant.

All POURING machines, however, have one common attribute; it is the price that may range from USD 40,000 to USD 100,000. This is the reason why all the existing Russian companies that use PUF POURING technologies can be clearly divided into two classes.

The first one comprises a relatively small (in nationwide terms) number of producers that own expensive professional pouring facilities. Such companies occupy up to 90% of the Russian PUF product market.

The other class is lots and lots of small and large enterprises that manufacture PUF products using the so called “hand pouring” method, which is characterized by a low efficiency, considerable feed losses (up to 30%) and a low product quality. The only advantage of the “manual” technology is that it requires no capital investment. Such business units’ production is mostly aimed at meeting their own demand for PUF products. It is difficult for them to compete with companies operating professional pouring equipment.

Obviously, even a USD 40,000 barrier is impassable for many would-be manufacturers of commercial poured PUF.
Situation may change dramatically now that since September 2003 we have started commercial production and supply of the NST LOW-PRESSURE POURING HEAD (ZG-006), which can be integrated into PENA-98 type units.

Why PENA-98 is the only Russian-made low-pressure unit capable of both SPRAYING and POURING Polyurethane Foam. The PENA-98P20UM model is complete with ZG-006 and is designed to manufacture small-diameter sectional insulation, small panels, features, and parts of furniture.

The latest development of NST Research & Production Company is the Low Pressure Pouring Machine capable of smooth output adjustment from 8 L/min up to 24 L/min. The machine is complete with a ZG-016 low-pressure pouring head.

The ZG-006 Head evenly mixes the components, forms a tough jet, and feeds the compound into any given cavity. The operation of this equipment is visualized in the Sectional Thermal Insulation Pouring Process Animation (click here).

ZG is complete with a Hydropneumatic Tank (HPT), which is used to thoroughly wash all ducts and working cavities of the Pouring Head using a solvent sprayed with the air jet.

 
ZG-006
ZG-016
Working mixture pressure inside Pouring Head, MPa (kg/cm2)

0.3-0.4 (3-4)
0.3-0.4 (3-4)
actuator
Pneumatic. Speed: 2000 rotations/min, Working pressure: 6.3MPa
Electric. Speed: 3000 rotations/min
Compressed air consumption providing normal operation of actuator, [L/min]
630
-
Minimum compressed air pressure providing normal operation of Pneumatic Actuator, MPa (kg/cm2)
0.75 (7.5)
-
Volume of solvent to be poured into HPT, liters
7-8
17-18
Overall dimensions of HPT with support, mm
400*400*550
600*600*550
Weight of unloaded HPT, kg
5.2
9.7
Compressed air consumption providing normal operation of HPT, L/min
70
120
Compressed air pressure providing normal operation of HPT, MPa (kg/cm2)
0.2-0.25 (2.0-2.5)
0.35-0.4 (3.5-4.0)
Overall dimensions of Pouring Head, mm
500*180*140
650*280*210
Weight, kg
5.5
24

Separate assembly of the ZG-006 and ZG-016 Heads has its own functional purpose but contributes to the general task of the design.

The set volume and design of the mixing chamber provides an even, uninterrupted, tough, waveless and spatter-free jet.
The agitator is specially tailored for thorough mixing and ejection of the compound.
The design of the mixing chamber with two inlet ducts for the components prevents the formation of “dead zones” where the mixture is decelerated.
The agitator rotation speed is optimal for thorough mixing of the components.
The proprietary structural concept of the rotor wheel-mixing chamber junction contributes to the leak-proofness of the cavity where the rotor connects with the drive shaft.
We have developed a system for high-quality and reliable cleaning of working cavities and all ducts of ZG with airborne solvent.
We have designed an offline system to feed pulverized solvent into the ZG head. The additional air flushing can also serve as emergency cleaning.

NST’s ZG Pouring Head has the following GUARANTEED functions:

The Pouring Head produces an even tough jet that has a stable diameter of 4 or 5 or 6mm (depending on the nozzle) and has no outflowing jet pulsation (provided the components are supplied steadily).
The mixing chamber provides a thorough stirring of the components, thus ensuring a proper chemical reaction and a high-quality foamed plastic.
When the service regulations are observed, the cleaning system guarantees a dependable wash.
However, the design and the structural concept of ZG’s mixer place certain RESTRICTIONS on its use.
The best way to use ZG-006 and ZG-016 is top pouring.
ZG-006 is designed for a maximum output of 6L/min; therefore the end product weight for single casting into one mold is limited to 2,5kg (provided the starting time is 20 to 25 seconds).
ZG-016 is designed for a maximum output of 24L/min; therefore the end product weight for single casting into one mold is limited to 10kg (provided the starting time is 20 to 25 seconds).
The ZG-006 and ZG-016 solvent washing system has an open-cycle design.



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