Liquid Acoustic Foam - GP-1 Vibration Damping Compound

The most advanced techniques in noise control involve the use of visco/elastic damping compounds which reduce noise most effectively when applied at the source of vibration. As the name implies, these compounds combine energy dissipation (viscous friction) and energy storage (elastic) characteristics. GP-1 is such a compound.

GP-1 is a vibration damping compound in liquid form for spray or trowel application on vibrating metal and plastic structures. It is a non-toxic, non-flammable water-based emulsion which can be air dried or oven baked to a tough coating.

The viscoelastic properties of GP-1 are specifically tailored to provide maximum damping between 60^oF to 120^oF.over a broad frequency range of 10 Hz to 20KHz. It can also provide useful damping over a broader temperature range of 20^oF to 180^oF.

GP-1 Provides a general-purpose, inexpensive vibration damping treatment. It can significantly add to the sales appeal of many types of mechanical and electrical appliances and machines by eliminating the tinny sounds caused by vibrating housings and enclosures.

gp1

Illustration above shows GP-1 Vibration Damping Compound being sprayed on curved surfaces. In a paste from it can be troweled on, as well.

In addition, GP-1 vibration damping increases the fatigue life of treated materials. This is of great importance not only as an economic factor but also as an invaluable safety measure in equipment that is constantly subjected to vibration.

Decay Rate Geiger Plate	45 dB/sec. @ 72^oF
% of Critical Damping	5% with 15% treatment by wt.
Specific Gravity (cured)	1.3
Color	Buff
Effective Temp. Range	- 45^oF to + 250^oF
Curing Time 70^oF	24 Hours
(1/16" thickness) 180^oF	90 Minutes
Resistance to:
Water	Poor unless painted
Petroleum	Good
Alkalis	Good
Fungus	ASTM G-21
Flame	ASTM G-635 0"/min
	ASTM E-162 Is <25
	NFPA-258 Dm <100
Thermal "k"	0.18

A thin coating on steel usually 1/2 metal thickness of 10% by weight completely eliminates tinniness from shock excitation. To damp enclosure walls subject to steady state vibration a coating equal to one or 1 1/2 times metal thickness (15-20% by weight) is recommended. The following wet treatments when cured will provide the following dry thickness and weight.

Wet Wt.Lbs./Sq. Ft.	DryThickness	Dry Wt.Lbs./Sq. Ft.
1.5	.125"	.93
1.25	.104	.77
1.0	.083	.62
.75	.063	.47
.5	.041	.31
.25	.021	.16

This table indicates the amount of GP-1 required to provide optimum damping effectiveness on 1000 square feet of steel sheet for a variety of thicknesses.

Metal Thickness	GP-1	Metal Thickness	GP-1
1/64"	125 lbs.	1/8"	1000 lbs.
1/32"	250 lbs.	3/16"	1500 lbs.
3/64"	375 lbs.	1/4"	2000 lbs.
1/16"	500 lbs.	5/16"	2500 lbs.
3/32"	750 lbs.	3/8"	3000 lbs.

Amount of Damping Attained at 72^oF
Treatment by Weight	10%	15%	20%	30%
% of Critical Damping	2.20	5.00	8.00	11.00
Loss Factor	0.04	0.10	0.16	0.22
Magnification Ratio Q	23	10	6	4.50

To apply GP-1 the metal surfaces must be clean. A vinyl wash primer or bonderizing are excellent treatments for steel. Trowel or spray a maximum of 1/4" thick coating.

Spray equipment should be 8:1 ration pump suitable for use in a 5 gallon pail or 55 gallon drum. Graco Pumps 225-837 or 225-575 and PowerFlo Gun 204-000 with 1/4" round nozzle and 3/4" I.D. fluid hose is recommended. Atomizing pressure should be 40-50 psi.

For Airless Spraying use a Binks 37 to 1 ratio pump or Graco Hydra President #226-164 28 to 1 without agitator. Use a Binks #43 gun with a 0.031" tip. It is necessary to remove both filters to prevent blockage. Here pressure should be 75 psi. When gun is not in use keep immersed in water. Gun, feed lines and pump should be cleaned after each shift.