The effect of condensation in clothing on heat transfer

A condensation theory is presented, that enables the calculation of the rate of vapour transfer with its associated effects on temperature and total heat transfer, inside a clothing ensemble consisting of underclothing, enclosed air, and outer garment. The model is experimentally tested by three experiments: I impermeable garments worn by subjects with and without plastic foil around the skin, blocking sweat evaporation underneath the clothing; 2 comparison of heat loss in impermeable and semipermeable garments and the associated discomfort and strain; 3. subjects working in impermeable garments in cool and warm environments at two work rates, with and without external radiation, until tolerance. The measured heat exchange and temperatures are calculated with satisfying accuracy by the model (mean error - 11, sd - 10 W/m2 for heat flows and .3 and .9 °C for temperatures, respectively). A numerical analysis shows that for total heat loss the major determinants are vapour permeability of the outer garment, skin vapour concentration, air temperature and clothing insulation. In the cold the condensation mechanism may completely compensate for the lack of permeability of the clothing as far as heat dissipation is concerned, but in the heat impermeable clothing is more stressful

An improved experimental method for local clothing ventilation measurement

This article was published in the serial, International Journal of Industrial Ergonomics [© Elsevier]. The definitive version is available at: http://dx.doi.org/10.1016/j.ergon.2013.10.009A clothing local ventilation measuring device based on the Lotens-Havenith steady state tracer gas method was developed and an improved experimental method for understanding local ventilation mechanisms was proposed. The local ventilation system can measure the arm, chest and back ventilation rates at the same time. Local ventilation mechanisms of an impermeable garment at two activities (static, walking) and two wind speeds (no wind, 1.2m/s) were studied, with a focus on determining the pathways of ventilation through the different garment openings. The results showed that local ventilation rates of chest, back and arm varied considerably over locations and conditions. As expected, ventilation rates were highest for all locations at walking with wind conditions. Ventilation mechanism changed at different walking and wind conditions. The main air exchange pathway for all locations was through the garment bottom. Wind had a greater impact on clothing local ventilation than walking. Relevance to industry: Clothing ventilation impacts worker's thermal comfort and safety directly both in the cold and heat. The new clothing local ventilation measuring device developed in this paper can measure both clothing local and whole ventilation. It can also help us to separate the different pathways for heat loss through clothing.© 2013 Elsevier B.V

Laboratory assessment of cold weather clothing

An overview of laboratory tests for cold weather clothing is provided starting from physical measurements on fabrics, and physical measurements on whole garments using thermal manikins. This is extended to human wear trials and climatic chamber experimentation. Insulation and vapour resistance are considered the most relevant parameters followed by wind and water proofness and moisture absorption properties. The use of test participants in wear trials is considered regarding the information provided by such tests. Tests for innovative fabrics (heated, variable insulation, phase change materials) are discussed. Finally testing of sleeping bags is considered

Recommendations for in vitro evaluation of blood components collected, prepared and stored in non-DEHP medical devices

© 2022 International Society of Blood Transfusion. Funding Information: T.R.L.K., S.B. and D.K. led the working party and contributed to the writing of the manuscript. A.L., O.E.S., M.D.W., C.G., P.J.M.B., R.E., L.L., S.T., T.N., W.B., J.E. and B.M. contributed to the writing of the manuscript. Publisher Copyright: © 2022 International Society of Blood Transfusion.BACKGROUND AND OBJECTIVES: DEHP, di(2-ethylhexyl) phthalate, is the most common member of the class of ortho-phthalates, which are used as plasticizers. The Medical Device Regulation has restricted the use of phthalates in medical devices. Also DEHP has been added to the Annex XIV of REACH, "Registration, Evaluation, Authorisation and Restriction of Chemicals" due to its endocrine disrupting properties to the environment. As such, the sunset date for commercialisation of DEHP-containing blood bags is May 27th 2025. There are major concerns in meeting this deadline as these systems have not yet been fully validated and/or CE-marked. Also, since DEHP is known to affect red cell quality during storage, it is imperative to transit to non-DEHP without affecting blood product quality. Here, EBA members aim to establish common grounds on the evaluation and assessment of blood components collected, prepared and stored in non-DEHP devices. MATERIALS AND METHODS: Based on data as well as the input of relevant stakeholders a rationale for the validation of each component was composed. RESULTS: The red cell components will require the most extensive validation as their quality is directly affected by the absence of DEHP, as opposed to platelet and plasma components. CONCLUSION: Studies in the scope of evaluating the quality of blood products obtained with non-DEHP devices, under the condition that they are carried out according to these recommendations, could be used by all members of the EBA to serve as scientific support in the authorization process specific to their jurisdiction or for their internal validation use.Peer reviewe

Kennis biedt meer bescherming dan een helm : Maken uitrustingssystemen PBM's overbodig?

Vakmedi

The actual insulation of multilayer clothing

Theoretische en experimentele gegevens laten zien dat kledingisolatie weliswaar sterk afhangt van bedekking van de huid, ingesloten lucht, houding, beweging en wind, maar toch goed te voorspellen is