Perforator test products

The two-hour desiccator and Perforator test results shown in Table II are also indicative of very low formaldehyde levels for phenolic panels. As with most of the results obtained in dynamic chamber tests, the uniformity of these test results, both within and between studies, indicates that the various phenolic panel products are quite similar with respect to their emitting potential. 

The purpose of this study was to evaluate laboratory formaldehyde release test methods for predicting real-life formaldehyde air concentrations human exposure levels, and health risk. Three test methods were investigated the European perforator test, the gas analysis method at 60 C and 3% RH, and the gas analysis method at 23 C and 55% RH. Different types of particleboard bonded with urea-formaldehyde and urea-melamine-formaldehyde resins were tested. The results were used to rank boards as a function of test method, conditioning, short-term humidity, and temperature variations during storage. Additional experiments were conducted in small experimental houses at a Dutch research institute. Our conclusions are that relative ranking of products is influenced by the test method and by change in relative humidity. The relationship between test method and release in real-life situations is not clear. In fact, it seems impossible to use laboratory measurements to predict real-life product performance of board if the board is not fully in equilibrium with the atmosphere. 

The incidence of perceptible formaldehyde in homes, offices and schools has caused widespread uncertainty about the safety of living with formaldehyde. This uncertainty was enhanced by the large scale installation of urea formaldehyde foam insulation (UFFI) because a substantial part of this material was made from small scale resin batches prepared under questionable quality control conditions, and was installed by unskilled operators (10). The only reliable way to avoid such uncertainty is to know the emission rate of products and develop a design standard that allows prediction of indoor air levels. The first and most important step in this direction was achieved with the development and implementation of material emission standards. As indicated above, Japan led the field in 1974 with the introduction of the 24-hr desiccator test (6), FESYP followed with the formulation of the perforator test, the gas analysis method, and later with the introduction of air chambers (5). In the U.S. the FTM-1 (32) production test and the FTM-2 air chamber test (33) have made possible the implementation of a HUD standard for mobile homes (8) that is already implemented in some 90% of the UF wood production (35), regardless of product use. 

If oil and water are mixed as an emulsion, dehydration becomes much more difficult. Emulsions can form as oil-in-water or water-in-oil if mixed production streams are subjected to severe turbulence, as might occur in front of perforations in the borehole. Emulsions can be encouraged to break (or destabilise) using chemicals, heat or just gentle agitation. Chemical destabilisation is the most common method and laboratory tests would normally be conducted to determine the most suitable combination of chemicals. 

When using peel tests on such products as belts to separate the plies, it can be difficult to obtain interfacial failure. Loha et al47 successfully used test pieces including a perforated metal sheet at the interface to measure rubber to rubber adhesion strength. 

While the perforator method also can be used for production control of MDF-boards it is questionable weather the method is feasable for plywood and other laminated wood panels. The two tested UF-bonded plywood boards e.g. although equal perforator values shows large difference in emission. 

This raises doubts about the reliability of predicting formaldehyde emission by using the perforator. However, on the other hand, each group of products corresponds to a given adhesive. This means that for a given adhesive a constant relationship exists between the perforator rate and the emission, as has been already demonstrated in earlier studies. Thus, this relation varies from one adhesive to another. Nevertheless, it will be necessary to carry out further tests in order to confirm that point. 

In the case of multi-ply packs some plies (particularly the foil) can be perforated but, as other plies may be continuous, leakage will not be detected by a vacuum test. However, this perforation may be sufficient to affect product life. This type of leakage may have to be detected by visual means (microscope) or by careful separation of the plies by suitable solvents. The other alternative is to subject the pack to a cycling climatic test, i.e. 15°C 50% RH and 37°C 90% RH with 12 h cycles. 

The technique that lends itself best to small-scale evaluation is low pressure agglomeration (Chapter 5, Fig. 5.10, and Section 6.2.2), which may be followed by spheroni-zation. Since in this method of pressure agglomeration a wet mixture is passed through the openings of a screen or a thin perforated sheet, very little pressure is exerted and it is essentially a shaping process [B.97]. Therefore, even if tests are performed on a small perforated die, in regard to product characteristics, the results are also representative for larger units. 

The influence of shear stress and pressure drawdown on solids production has been demonstrated in large-scale laboratory tests (38). Short bursts of solids, from perforation clean-up, and productivity improvement occurred after each increase in effective stress or drawdown. 

Most countries have standard sieve specifications and sieve analysis procedures. These specifications and procedures are usually generic and can be used for a wide variety of products, including fertilizers. The ISO has a series of international standards for test sieves [10] including (1) Test sieves - Woven metal wire cloth and perforated plate - Nominal sizes of apertures (ISO 565) ... 

Preform pre- f6rm [L praeformare, fr. prae-+ formare to form, fr. forma form] (1601) vt. (1) The test tube shape that is used to form the final blown product in injection blow molding. (2) A compressed tablet or biscuit of plastic composition used for efficiency in handling and accuracy in weighting materials, particularly thermosets. (3) Formed perform. (4) A pre-shaped fibrous reinforcement formed by the distribution of chopped fibers or cloth by air, water flotation, or vacuum over the surface of a perforated screen to the approximate contour and thickness desired in the finished part. (5) A pre-shaped fibrous... 

A similar program also conducted by the automotive industry is also a collaborative effort between AISI s Corrosion Task Force and SAE/ACAP led to the determination of appropriate test methods for predicting perforation (inside-out) corrosion on automotive coated sheet products. Development/determination of appropriate test methods for predicting perforation corrosion on coated sheet products [56,62,65]. 

---