Mass and heat transfer


Laboratory of Transport Phenomena

SCOPE OF THE LABORATORY ACTIVITIES

	plastic and
	cellular plastic materials and rubber (neoprene, polyurethane)
	special building materials and products
	floor textiles
	natural and synthetic skivers

TESTING - LIST OF SELECTED PROPERTIES:

Steam permeability

Testing of steam permeability are executed by gravimetric method, it means, that increase of the weight is observed at transport of steam trough the barrier of analysed specimens in surrounding of steams of saturated solution of the salt to surrounding of dry air with dried silica gel. Result is permeability parameter for steam in stated climatic surrounding on condition of stationary state.

Volatile substance permeability

Transport effects is possible observe also at solvents, volatile liquids and propellants. At that testing is gravimetric observed volume decrement of liquid, which diffuse trough the wall of tested material in dependence on time. Result is permeability parameter for liquid on condition of stationary state.

Gas permeability

Measurement gas permeability (nitrogen, oxygen, air, hydrogen, helium, carbon dioxide etc.) at above materials take place at testing temperature 23°C. But it`s possible measure out also the thermal dependence of permeability parameters for gas to temperature 90°C. Principle of this test is measurement the time dependence of gas pressure, which diffuse trough the assessed specimen from high pressure part of plant to low pressure part. Result is parameter ? transmission factor for gases and value of the gas transmission.

Air permeability

This test is applicable especially at the textile materials. This parameter is ranked among the physiological parameters of textiles. Principle of this method is designation of the speed of current of air entering upright trough the specimen surface at above hydraulic gradient. Result is usually presented at m/s.

Detection of viscosity, viscosity number, limit viscosity number

Cinematic and dynamic viscosity are the most often detected viscosity characteristics of liquids. Either limit viscosity number or only viscosity number of the watched polymer, which is melted in suitable low molecular dissolvent, is determined for evaluation of the polymer molecular structure. For such measurements there are used glass capillary viskosimeters [with pendulous level] in connexion with equipment for automatic measurement of the flow time [Viscotimer S]. Equipment enables measurement in the temperature interval from -20°C till +100°C.

In the case of concentrated solutions and polymer pastes their relative viscosity is defined by ball ? Hoppler`s rheoviskozimeter at temperatures from +20°C to +100°C. Measurement viscosity is usually supplemented by density determination of above liquids. In such case the measurement are executed by densimeters, pycnometric method, or double weighing on electronic scales.

Pressurized water permeability

The test controls the liquid pressure, which will not penetrate the surface material. Result is usually presented in cm of water column or in Pa. The test is often desired at various types of foils used in building industry and in textile materials for the top cloth protecting against climatic effects.

Water-repellent - Spraytest

Material surface wetting resistance is simulated by defined surface spraying. Result is usually presented by ratio of repelled liquid.

Penetrace

At test is measured the ratio of liquid penetrating trough the tested material and ratio, that was repelled by its surface. Test dissembles short-term contact with liquid chemical. Result is index of penetration and index of repellency for above type of liquid chemical. The test is one of the indicators of usability of materials for production of protective instruments.

Permeation ? chemical permeability

At test is measured the time demand to penetration of chemicals trough the tested surface. Test dissemble the surroundings of long-term contact of liquid chemical with the surface of the sheet materials.

OFFER OF SERVICES

Laboratory testing serves as basis of:

	conformity assessment according to appropriate Czech legislation and/or European Directives
	product or materials characteristics certification
	product's quality evaluation
	product certification
	issue of an ATEST
	ssue of a Test Report of Accredited Laboratory