Effect of moisture content on some

Plant Species of San Jacinto Mountain: The information on this page is still correct for the cones I had seen inbut with further experience I have learned much more about the variation in these species. In particular, the prickles of the two species are quite variable, and I've found a number of Jeffrey cones that are prickly even when closed.

Effect of moisture content on some

Additional Resources Moisture in buildings is a major contributor to mold growth, unhealthy buildings, and poor indoor air quality.

Wetting of building walls and rainwater leaks are major causes of water infiltration, but so is excessive indoor moisture generation. Preventive and remedial measures include rainwater tight detail design; prevention of uncontrolled air movement; reduction of indoor air moisture content; reduction of water vapor diffusion into walls and roofs; selection of building materials with appropriate water transmission characteristics; and proper field workmanship quality control.

A successful method for deterring rainwater intrusion into walls is the rain screen approach, which incorporates cladding, air cavity, drainage plane, and airtight support wall to offer multiple moisture-shedding pathways.

Rain Screen The concept of the rain screen principle is to separate the plane in a wall where the rainwater is shed and where the air infiltration is stopped.

In terms of construction, this means that there is an outer plane which sheds rainwater but lets air freely circulate, and an inner plane which is relatively airtight.

Effect of moisture content on some

In terms of pressures, there is no pressure differential across the outer pane and there is a significant pressure differential across the inner plane. Because there is no pressure difference across the outer plane, there is no driving force to move water indoors; because there is no water present at the inner plane, no water will penetrate the inner plane despite the presence of the driving force of the pressure difference.

Mold Molds are part of the natural environment and are present everywhere. They are usually not a problem indoors. The medical community appears to be divided regarding the threat of mold, but seems to agree that some people with allergies are sensitive to mold and that in sensitive individuals mold can lead to respiratory diseases.


To grow, or to establish itself, mold requires at least four elements: Carried by air currents, mold spores can reach all surfaces and cavities of buildings. To control mold growth, designers should focus on controlling moisture indoors and on the temperatures of all surfaces, including interstitial surfaces within walls.

In addition to mold, other organisms such as bacteria, mites, cockroaches, and insects that are known to infest buildings also depend on moisture. For all these reasons, moisture control must be a primary consideration in both the design of new buildings and in the renovation of existing structures.

The remainder of this Resource Page will focus on the sources of excessive moisture and some strategies to prevent water infiltration into buildings. Moisture Dynamics Concepts and Definitions Psychrometrics: The study of air-water mixtures is called psychrometric.

The relationship between air temperature, moisture content, and humidity has been codified in a diagram called the psychrometric chart that is indispensable for understanding condensation.

Among other things, it indicates the dew point temperature of any air-water vapor mixture. Water Vapor Permeance and Permeability: Permeability is a material property; permeance is a product property. For board materials, usually permeability is given; for thin membranes, it is customary to provide their permeance.

The rate of water vapor transmission through unit area of a flat product induced by unit vapor pressure between its two surfaces. The time rate of water vapor transmission through unit area of a material of unit thickness induced by unit vapor pressure difference between its two surfaces.

Permeability is also sometimes given as perm per inch. Vapor and Air Retarders: These materials inhibit the uncontrolled flow of air and water vapor through the building envelope: A membrane or paint film having a water vapor transmission rate of less than one perm, used to reduce the rate and volume of water vapor diffusion through ceilings, walls, or floors.

Membranes are generally thin flexible materials, such as polyethylene, while coatings are typically of asphaltic, resinous, or polymeric composition and applied by trowels or brushes for more product information, see Product Suppliers and Manufacturers section below.

A common type of air retarder is composed of fiber-reinforced polyolefin. All joints and seams in air retarders must be sealed to create an effective air retarder.

ASTM International specifies that a material must have a perm rating of 5. So that it is possible to seal an air retarder correctly, the wall needs to be detailed carefully and with the sequence of installation in mind.

A membrane meeting the water vapor resistance rating of a vapor retarder combined with the air infiltration characteristics of an air retarder, used to restrict both the rate and volume of air and of water vapor through ceilings, walls, and floor elements.

Installation of Combined Air and Water Retarder The same material can be both an air and vapor retarder.

Humidifiers: Air moisture eases skin, breathing symptoms

Courtesy of Commonwealth of Massachusetts The photo shows a system that uses a peel-and -stick material as both the vapor retarder and air retarder. The material is installed over the gypsum sheathing but on the warm-in-winter side of two inches of extruded polyethylene insulation.

Courtesy of Commonwealth of Massachusetts Moisture Movement: Moisture can move through and into building components in three major ways: Rainwater Impingement and Leakage: Even though rain is infrequent in some parts of the U.About Moisture and Wood.

The durability of wood is often a function of water, but that doesn't mean wood can never get barnweddingvt.com the contrary, wood and water usually live happily together. There is always some mold everywhere – in the air and on many surfaces. Molds have been on the Earth for millions of years.

Mold grows where there is moisture. Exposure to damp and moldy environments may cause a variety of health effects, or none at all. Some people are sensitive to molds. For. Technical Bulletin 4 more consistent and uniform with respect to moisture content than ever before in the history of paper manufacturing.

When properly packaged and stored. Optimization of Bleaching Process Introduction. The bleaching of edible oils and fats is a part of the refining process of crude oils and fats, which removes contaminants that adversely impact the appearance and performance of these triglyceride (triacylglycerol)-based materials.

Moisture is the presence of a liquid, especially water, often in trace barnweddingvt.com amounts of water may be found, for example, in the air (), in foods, and in various commercial barnweddingvt.comre also refers to the amount of water vapour present in the air..

Moisture control in products. Control of moisture in products can be a vital part of the process of the product. Moisture sensitivity level relates to the packaging and handling precautions for some semiconductors.

The MSL is an electronic standard for the time period in which a moisture sensitive device can be exposed to ambient room conditions (30 °C/85%RH at Level 1; 30 °C/60%RH at all other levels).. Increasingly, semiconductors have been manufactured in smaller sizes.

Moisture sensitivity level - Wikipedia