YY/T 0471.2-2004Test methods for primary wound dressings - Part 2: Moisture vapour transmission rate of permeable film dressings (English PDF)

2.1 moisture vapor transmission rate (MVTR)

permeability of materials to the passage of water molecules from skin contact site to the external atmosphere under controlled conditions of humidity and temperature

2.2 permeable wound dressing

wound dressing that permits moisture vapor to pass from the skin or wound through it to the external atmosphere

2.3 primary wound dressing

material or combination of materials, in any shape, form or size that is intended to remain in direct contact with a wound

Note: primary wound dressing are used as mechanical barriers, for the absorption or transmission of exudates, to manage the micro-environment of the wound, and can enable the wound to heal by primary or secondary intent. Devices which have a metabolic, pharmacological or immunological interaction as their primary intent are excluded.

3.1 Test conditions

Unless otherwise stated, condition the test sample and carry out the tests at a temperature of (21±2)°C and a relative humidity (RH) of (60±15)%.

3.2

Moisture vapor transmission rate of a wound dressing when in contact with moisture vapor

3.2.1 Significance and use

The test is intended for the evaluation of the moisture vapor transmission rate of a wound dressing when it is in contact with moisture vapor.

The test measures moisture vapor transmission through dressing by mass differential. Entrapment of liquid can lead to serious consequences for skin integrity. Dressing should have sufficient permeability to moisture vapor to prevent liquid collecting under the dressings.

Note: the test is suitable for use with, for example, thin film wound dressings.

3.2.2 Equipment

3.2.2.1

Five clean, dry cylinders, made of corrosion-resistant material with an internal diameter of (35.7±0.1)mm (cross-sectional area of 10cm2) having a flange at each end and able to accommodate 20mL deionized water for each (An example of a cylinder that has been found to be adequate is given in Figure 1).

One end of the cylinder is an annular clamping plate with an orifice area of 10cm2; the other end of the cylinder is a metal cover plate with a diameter equal to that of the flange. A sealing ring is also advisable to ensure an effective seal against the flange. The plates at both ends are clamped in position against the flanges.

3.2.2.2

Balance, capable of weighing 100g, with an accuracy of 0.0001g.

3.2.2.3

Humidity meter, capable of detecting whether or not the 20% relative humidity (RH) limit has been exceeded.

3.2.2.4

Oven or incubator, having a circulating air and capable of maintaining a temperature of (37±1)°Cand being of a design to distribute the air evenly so as to maintain relative humidity (RH) at less than 20% throughout the test.

3.2.2.5

Scalpel, or alternative cutting equipment.

3.2.3 Procedure

3.2.3.1

Using the flange of clamping plate as a template, cut out a sample of the material to be tested.

3.2.3.2 Add sufficient water at room temperature (minimum

20°C) to leave an air gap of (5±1)mm between the liquid surface and the sample when clamped in place 3.2.3.3 Place the circular sample exactly over the flange D of the test container. Clamp it in place without stretching the sample, using the clamping plate/clamps to give a watertight seal. If the specimen has an adhesive coated surface, place the adhesive side to the cylinder flange. For non-adhesive or pattern coated materials, take care to ensure a complete seal. Repeat the procedure four times so as to prepare five samples.

Note: to ensure good sealing, a small amount of sealant such as petrolatum can be applied to the flange.

3.2.3.4

Weigh and record the mass (W1) of the container, sample and liquid to the nearest 0.0001 g.

3.2.3.5

Place the container in the oven/incubator at temperature of(37±1)°C with the sample uppermost.

3.2.3.6

After 18h to 24h, remove the container from the oven/ incubator, and record the test period (T) to the nearest 5min.

3.2.3.7

Immediately reweigh the container, sample and liquid and record the mass (W2) to the nearest 0.0001g.

3.2.4 Calculation of results

3.2.4.1

Calculate the moisture vapor transmission rate (MVTR) using the formula: