Momentary contact

A loop tack (Fig. 2c) test consists of allowing a tear-shaped loop of conditioned tape to drape into contact with a test surface of specified area (usually 25.4 x 25.4 mm), with the force of contact limited to the weight of the tape itself (ASTM Ref. D-6195). The ends of the loop are held in a tensile tester. After a momentary contact time the tester is engaged and the tape is removed at a specified speed. The maximum in the removal force is ordinarily observed just at the point where the two peel fronts Join. The value is reported in a force per area of tape width, or lb in. -. While this tack test has some popularity, it is perhaps more of a very short dwell time peel test, and it has variables more associated with that test, especially backing effects, since heavier backings lead to higher tack values. 

Momentary contact switch SW1 enables the state of OA-1 to be changed at will. A control (R25) has been added that permits the triangular wave to be moved (offset) along the voltage axis without influencing its time course. Note... 

Creases formed in the film prior to the emboss nip will become welded into it as longitudinal faults. Such creases usually are caused by release of film from the calender roll in the form of an extreme arc, or by a total failure to control the tension between the calender and the emboss nip. Momentary contact of the film with the surface of the stripping rolls also may cause creases. 

Transformer ignition circuit for bomb calorimeter. The switch is a momentary-contact push switch that is only on when it is held down. Release the switch if ignition does not occur after about 5 s (the pilot light will indicate when the fuse wire bums through). The choice of resistor R will depend on the type of calorimeter and the length of fuse wire to be used (a current of 3 to 4 A is desired). 

Eluted material almost always includes unwanted extraneous matter co-extracted from the paper or thin-layer chromatogram. Thus it is advisable to use the eluent from a blank area as a reference solution. Contamination from plasticisers, solvents, and dirty glassware can also be a serious problem when a spectrum has to be obtained from a few micrograms of a compound. Even momentary contact of dry adsorbent with plastic tubing can remove appreciable quantities of plasticisers. Hence the following precautions should be taken ... 

Mixed film conditions occur when a loss of the film resulting in momentary contact between the two surfaces is apparent. This occurs as a response to momentary variations in loading, called shock loading, that collapse the film and result in physical contact of opposing asperities [20]. 

In other adsorptions, the reduction occurs during a momentary contact or adsorption, and the question of more permanent adsorption depends on the solubility of the product that is formed. Ferric chloride dissolved in distilled water, when treated with carbon, is reduced and adsorbed hydrolytically as ferrous hydroxide. If the solution is acidified sufficiently, the adsorption is negligible and the newly formed ferrous ions appear in the solution. 

As the A value characterizes, in fact, the adhesional strength of bonding at a momentary contact between the polymers (r —> 0), this parameter does not account for the contribution of diffusion events in the adhesional interaction. The A value takes into account only energy interactions of unlike macromolecules in zones of interphase contact (47). 

In flame treatment, plastic objects such as bottles and film are passed through an oxidizing gas flame. Momentary contact with the film causes oxidation of the surface, which makes it receptive to material used in decorating the product. 

Figures 7.3 and 7.4 show the plots of normahzed force (force/particle radius) versus piezo displacement as a colloid probe was retracted from the membrane surface for ES 404 and XP 117, respectively. In making such measurements, the colloid probe first had to be brought into (momentary) contact with the membrane surface. It was reported that the loading forces for such contact have an influence on the measured adhesive force [22,37]. The loading forces for the curves shown are 223.5 nN (Fig. 7.3)...

Certain hand-held powered tools must be equipped with a momentary contact on-oflE control switch and lock-on control provided that turnoff can be accomplished by a single motion of the same Anger or fingers that turn it on. Others may be equipped with only a positive on-oflf control switch. Some hand-held powered tools must be equipped with a constant pressure switch that will shut off the power when the pressure is released. 

Make sure safety switches requiring momentary contact for on-off control are in working order and not over-ridden on the tools they should be on (such as drills, tappers, fastener drivers, horizontal, vertical and angle grinders with wheels larger than two inches in diameter, disc Sanders, belt sanders, reciprocating saws, saber saws, and other similar equipment). 

Use Start of the fully guarded momentary contact type on equipment or operations sensitive or very dangerous in the event of inadvertent start-up. Otherwise, flush momentary type buttons shall be used. 

Use Normal Stop buttons of the extended momentary contact type. 

Control, three-wire Control function incorporating a momentary contact pilot device and a holding circuit contact to provide undervoltage protection. 

Table II Mortality (%) of mosquitoes after 24 hrs of momentary contact to...

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