Protective Heat (Heat Series Book 3)

We explain exactly how this works in our blog series "How safe is safe": Part 1 Part 2. The European standard DIN EN regulates the requirements for clothing to protect against rain as part of protective workwear. Two performance parameters are specified for this protective clothing:. Class 3 has the highest water penetration resistance and fulfils the highest requirements. Water penetration resistance WP is measured in pascals Pa and is the hydrostatic pressure held by a material. The term "water column" is often used, which is then given in millimeters.

Both the material and seams are tested. Class 3 has the lowest water vapour resistance and fulfils the highest requirements. If the garment has a Ret value of class 1, it must carry the warning "limited wearing time" after this number. High-visibility clothing is a visual signal of the wearer's presence — and makes the wearer conspicuous in dangerous situations, in all possible light conditions during the daytime and also in the dark when seen in headlights.

Visibility is achieved by making a sharp contrast between the clothing and the background against which it is seen. Protective clothing therefore needs to be chosen according to the predominant background in order to ensure maximum protection.

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High-visibility clothing generally consists of a basic fluorescent material and a retro-reflective material. The minimum areas in square metres on the background and reflective material determine the class of high-visibility clothing. DIN EN describes the specifications for protective clothing for areas where there is a risk of entanglement in moving parts. Duly certified protective clothing minimises the risk of entanglement or textiles getting caught in moving parts if the wearer is working at or near machinery or equipment with dangerous movements.

Test method for measuring surface resistivity Part 2: Test method for measuring vertical resistance Part 3: Test method for measuring charge decay Part 4: Testing clothing standard currently in progress Part 5: Performance requirements for material and construction This is protective clothing with antistatic characteristics. This clothing reduces electrostatic charging of personnel and the occurrence of inflammable static sparks.

It is required in areas where explosive atmospheres can occur. The standard defines the electrostatic requirements for clothing to avoid inflammable discharges. Protective clothing for welding and allied processes in accordance with EN ISO protects the wearer from small molten metal splashes, brief contact with flames, and radiant heat from the electrical arc.

The clothing can be suitable for persons during welding and allied processes where the same type and similar hazards occur.

Disposable Coveralls | Heat Resistant Clothing | uvex safety

The protective effect is achieved with flame retardant fabric in conjunction with specific processing properties, which are defined in EN ISO One criterion for classification as protective clothing for use in welding is limited flame spread. Testing this criterion involves analysing how the fabric burns after being exposed to a small vertical flame. Method A — surface ignition: The flame is applied to the centre of the sample. Method B — bottom edge ignition: The flame is applied to the bottom edge of the sample. Protective clothing of standard EN ISO — clothing to protect against heat and flames — protects workers who come into brief contact with flames and at least a type of heat.

A test criterion for classification as protective clothing for workers exposed to heat is the limited flame spread in accordance with EN ISO previously DIN EN , in the same way as the test criterion for protective clothing for use in welding code letter A. The type of heat is defined by the codes B to F. The heat that occurs can be convective code letter B , radiant code letter C , caused by molten aluminium code letter D or molten iron code letter E splashes, as contact heat code letter F or as a combination of these forms.

In addition to the code letters, performance levels 1 to 4 are also specified for this protective clothing. The higher the performance levels, the higher the protective effect of the relevant item. The protective effect is achieved with flame-retardant fabric in conjunction with specific processing properties. Additional performance levels are defined for heat transfer:. The full clothing can be optionally tested to predict burns.

Introduction

Protective clothing in accordance with the DIN EN standard — protective clothing against the thermal risks of an electric arc — refers to thermal clothing. This clothing is suitable for work in the low-voltage range where thermal risks can occur because of an electric arc.

The measurement is taken using the CENELEC arc box test in which energetic thermal insulation measurements and a quantitative evaluation of the burn risk are carried out. The clothing is not, however, electrically insulating protective clothing in accordance with EN If the front of the product in the case of jackets for example is in a higher protection class than the back, the entire front, including the sleeves, must be in this higher class.

The different performance of the back must be clearly marked. The standard aims to prevent potential hazards from inadvertent, brief and occasional contact with small flames. This relates to situations where there are no significant risks from heat or any other heat sources. Protective clothing that complies with this standard is not suitable if additional protection is needed because of a risk from heat and flames. The standard also defines additional requirements for protective clothing, including mechanical requirements and requirements governing labeling and the supply of information from the manufacturer.

Protective clothing in accordance with EN ISO consists of several one or multi-layered garments or a single garment. Each material assembly is assigned to an index 1, 2 or 3 for limited flame spread in accordance with testing as per ISO DIN EN certified products. Standard DIN EN regulates the requirements for whole-body protective suits or full protection suits with sealed connections between different parts of the clothing if present.

Chemical protective clothing is essentially divided into categories according to specific applications. The test criteria for protective clothing against liquid chemicals can be proven using specific test methods. Jet test used for liquid-tight protective suits — type 3 For the jet test for liquid tight protective suits, the protective clothing is worn by a test person over an absorbent overall. The material undergoes predetermined stress testing while a specific volume of marker liquid is blown at the test person from a test apparatus using a strong air stream.

The liquid-tightness of the protective suit is determined via a visual inspection of the overall worn underneath. Spray test used for spray-tight protective suits — type 4 The functionality of type 4 spray-tight protective suits is tested by way of a liquid spray test. The spray test is carried out in the same way as the jet test, with the difference that the marker liquid is blown from the test apparatus in bursts of finely atomised spray. EN certified products. The European standard ISO regulates the minimum requirements for type 5 chemical protection suites. This covers whole-body protective suits that protect the wearer against particles and aerosols of solid chemicals.

The garments specified by the standard cover the torso, arms and legs with or without a hood or foot protection. In our study, the changes in the oxidative stress level were closely associated with local microcirculation disturbances, such as decreased microvascular blood flow and abnormal vascular reactivity. Supplying SOD to the rats effectively inhibited ROS generation during heat stress, thus improving the local microcirculation disturbances caused by oxidative stress. The findings of this study also demonstrated that the SOD activity increased gradually in the spinotrapezius of rats injected with Xuebijing, and Xuebijing injection also effectively decreased the ROS level in the local spinotrapezius tissues.

In this study, at the onset of heat stress, the MAP decreased significantly; this is likely because body fluid loss and the regulation of body fluid distribution in the early stage of heat stress can lead to a decrease in the effective circulating blood volume. The hemodynamic characteristics of heat shock are similar to those of hemorrhagic shock. Previous studies have shown that in the early phase of hemorrhagic shock, the microvessel V RBC and blood flow rate decrease In our study, when the rats were pretreated with Xuebijing or SOD, the V RBC and blood flow rate in microvessels were significantly better than those in the vehicle group, suggesting that Xuebijing could protect against the heat-stress-induced decrease in the blood flow rate in microvessels.

In this study, however, the changes in the arteriolar and venular diameters from the initiation of heat stress to the onset of severe heat stroke were not statistically significant. Previous studies on hemorrhagic stroke showed that the arteriolar and venular diameters decreased indicating microvessel contraction in hemorrhagic stroke It is known that during shock, the vasoconstriction of vessels of the skin favors the shifting of blood toward more crucial organs such as the heart, brain or liver. Nevertheless, a recently study demonstrated that maintenance of functional capillary density was the only critical microvascular parameter correlated with survival in severe hemorrhagic shock Thus, our findings further suggested that the decrease in the blood flow volume was mainly caused by the decrease in blood flow velocity in the microvessels in the period from the initiation of heat stress to the onset of severe heat stroke.

This study found that the MAP decreased in the early stage of heat stress. We speculated that the MAP decrease in this phase could be associated with self-regulation, such as the re-distribution of body fluid.

However, the MAP was restored to the level observed before heat stress when the core temperature increased to This restoration could be associated with the occurrence of heat stress responses. Previous studies on stroke 12 showed that heat stress could promote cellular metabolism and reduce visceral blood flow, thus inducing ischemia and hypoxia in the intestine and liver cells. Therefore, visceral hypoperfusion, as well as changes in immune functions and intestinal barriers, could occur in heat stress.

In addition, endotoxin leakage and inflammatory factor release also increased, and vascular endothelial growth factors such as NO and endothelin were released. The cytokines and inflammatory factors induced by high temperature could influence sweating and vascular bed changes to affect thermal regulation mechanisms and alter vascular permeability and visceral microcirculation, thus causing hypotension, high fever, and even multiple organ dysfunction.

These findings indicated that the clinical application of anti-oxidants or Xuebijing could be an effective method for treating severe heat shock. This study also showed that the microcirculatory blood flow volume including the arteriolar and venular volumes and the MAP decreased in the early stage of heat stress. However, when the core temperature reached 38— By contrast, the microcirculatory blood flow volume did not recover with the improvement in systemic hemodynamics; instead, the blood flow volume decreased progressively until the rats died.

These findings suggested that in the heat stress model, microcirculation disturbances appeared before systemic circulation disturbances, and the persistence of microcirculation disturbances could be an important factor underlying the difficulty in treating shock and its poor prognosis. Early studies have shown that dehydration is also a typical manifestation of stroke 4.

This study showed that with the increase in temperature, the rats in the three groups all showed mild-to-moderate body fluid loss. However, providing normal saline or SOD before heat stress induction did not improve the dehydration. We speculate that the mild-to-moderate dehydration was not associated with the prognosis of severe heat shock in rats.

The findings of this study showed that SOD activity in local tissues decreased gradually during heat stress, while the level of ROS increased gradually, which was associated with poor prognosis. Aprevious study on sepsis 25 showed that normal capillaries maintained homogenous blood flow from endothelial cells to precapillary arterioles; however, such blood flow could be blocked by sepsis.

In addition, sepsis also disturbed the activation of endothelial cells, lymphocytes, and platelets. In other words, microcirculation disturbances could be an important factor causing multiple organ dysfunction and elevated mortality. Thus, our findings are similar to those of previous studies. We also found that using Xuebijing or anti-oxidants effectively inhibited the increase in ROS during heat stress and improved the microcirculation, thus improving the survival time of rats after severe heat shock and finally improving the prognosis of rats with severe heat shock.

In summary, in the present study, we continuously observed the microcirculation in the spinotrapezius of rats with severe heat shock and measured the total SOD activity and ROS level changes. The findings revealed the changes in the oxidative stress levels in local tissues during heat stress, showed an association between the changes in the microcirculatory blood flow volume and those in the systemic circulatory blood flow volume, and demonstrated that a gradual decrease in SOD in local rat tissues could result in increased ROS levels, which in turn induced microcirculation disturbances.

The microcirculation disturbances occurred before systemic circulation disturbances and could be an important factor causing circulatory failure after severe heat shock. Xuebijing reduced the local ROS level and protected the microcirculation during heat stress, thus improving the prognosis of rats with severe heat shock. Standard food and water were provided to the rats during the study. Forty of the rats were divided into 4 groups 10 in each group as follows: All the rats except for those in the control group were placed in an infant incubator for heat stress exposure.

The 27 rats were divided into 3 groups as follows: In each group, the rats were further divided into three subgroups as follows: This study was approved by the Animal Ethics Committee of Southern Medical University and conducted according to the guidelines and regulations for the use and care of experimental animals in China. In addition, this study also minimized the number of animals and the discomfort of the animals, according to the guidelines for experiments with living animals in China. The SOD inhibitory rate was calculated using the following equation:.

The weight of the spinotrapezius muscle was accurately measured. Part of the supernatant was used to determine the protein concentration by the BCA method. A flow cytometer was used to analyze ROS levels. Preparation of the spinotrapezius muscle and intravital microscopy: The spinotrapezius muscles are located anatomically in the mid-dorsal region, originating in the lower thoracic and upper lumbar regions and inserted at the scapular spine.

Spinotrapezius muscles were prepared as previously described by Gray Briefly, the spinotrapezius muscle was exteriorized with marginal damage to the fascia. No evidence of local trauma, which might impact regional blood flow in this model, was reported. The solution was heated to prevent loss of heat via perfusion.

The exposed spinotrapezius muscle was fixed at six equidistant sites around the caudal periphery to ensure consistent shape and length of the selected vessels. Assuming cylindrical geometry, the blood flow rate was calculated using the following formula: The prepared spinotrapezius muscle was covered with thin gauze, which was continuously perfused with a heated Krebs—Henseleit bicarbonate-buffered solution. Then, right femoral artery catheterization was performed. SOD and Xuebijing were injected accordingly as described earlier.

One hour later, the rats were placed in an infant incubator for heat stress exposure, and the microcirculation was observed by intra vital microscopy. Since the rats had to be removed from the infant incubator at each time point, the microcirculation observation was conducted as fast as possible to avoid allowing the core temperature of the rats to drop Fig.

Experimental protocol and outline. Surgery included spinotrapezius preparation and right femoral artery catheterization. The microcirculation was observed by intravital microscopy. All rats were kept in an infant incubator for heat stress environmental temperature: The change of weight was calculated as follows: Analysis of variance for repeated measurements was used to compare the differences between groups at different time points. Pair wise comparisons were conducted using t tests. Jiang conceived and designed the experiments; H.

Jin performed the experiments; H. Chen analyzed the data; H. Jin wrote the manuscript; and L. Su reviewed the manuscript and supervised the research. All authors read and approved the final manuscript. Hui Jin and Yi Chen contributed equally to this work. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

National Center for Biotechnology Information , U. Published online Mar Author information Article notes Copyright and License information Disclaimer. Received Sep 7; Accepted Mar 1.

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To view a copy of this license, visit http: Abstract This study was conducted to explore underlying mechanism of microcirculation dysfunction and protectiverole of Xuebijing in heat stroke. Introduction Despite several decades of studies, heat stroke remains a major clinical problem with high morbidity and mortality and a high incidence of multiple organ dysfunction syndromes MODS.

Results Changes of SOD activity in spinotrapezius tissue homogenates during heat stress SOD activity decreased gradually with the increase in the core temperature during heat stress compared with the control group. Open in a separate window. Discussion Heat stroke can be classified as classic heat stroke or exertional heat stroke according to the etiology 4. Table 1 Grouping and number of animals for microcirculatory observation.

The SOD inhibitory rate was calculated using the following equation: Measuring the ROS level in the spinotrapezius The weight of the spinotrapezius muscle was accurately measured. Microcirculation monitoring Preparation of the spinotrapezius muscle and intravital microscopy: Notes Competing Interests The authors declare no competing interests.