Agricultural engineering

Vapor density

Why is vapor density important to know?

Basically, vapor density is the weight of a vapor or gas compared to an equal volume of air. Air is rated as 1. Vapors heavier than air accumulate in low areas. Vapors lighter than air rise. Knowing which way vapors will move is important for human health and safety.

Consider as an example the common solvent toluene, which has a vapor density of 3.2. The toluene vapors will sink and concentrate in low areas. The solvent may be barely discernable to an adult working from a standing position, but along the floor of the work area the vapors could achieve a dangerous concentration. If a pilot light or other source of spark or flame ingited near the concentrated vapors, it might cause a flash or explosion. A person breathing vapors at that concentrated level could also be at risk.

In another practical application, anyone dealing with an accidental release of the solvent from an industrial facility must know which way the vapors will travel in order to know how to safely position emergency responders. You don't want to be uphill and upwind of a lighter-than-air chemical release.

Marie Steinwachs
Director
Missouri Environmental Assistance Center

Wind power generators

I am interested in seeing the wind power generators in Gentry County. Can you give me the location and directions to view them?

These turbines are located on Highway 169 just north of King City. You will be able to see the turbines from the road or from some of the adjoining county roads. However, each turbine is located on private property, so you will only be able to view the project from the public roads.

The Bluegrass Ridge Wind Farm consists of twenty-seven Suzlon S88 turbines with a nameplate capacity of 2.1 megawatts (MW) for a total project size of 56.7 MW. Bluegrass Ridge is projected to provide enough "green energy" to power about 34,000 homes.

Another project nearing completion is the Cowbranch Wind Energy Center located on Highway 136 between Rock Port and Tarkio in Atchison County. The wind farm consists of twenty-four Suzlon S88 turbines, each with a nameplate capacity of 2.1 MW, for a total project size of 50.4 MW. Cow Branch is expected to provide enough clean, renewable energy for 30,000 homes. About two-thirds of these windmills are erected, and more are going up every day.

Jim Crawford
Natural Resource Engineering Specialist

Tractor tire ballast

I read William W. Casady's G1235, Tractor Tire and Ballast Management. What is used for ballast on tractors?

Tractors are ballasted with cast iron weights designed specifically to fit onto the tractor either on a bracket as you may have seen on the front of many tractors, or on the rear wheel assembly. Large tires on slow-speed tractors are often filled with a solution of water and calcium chloride or other common salt or antifreeze solution to prevent freezing. We recommend using cast iron weights that can be added or removed quickly to adjust the weight of the tractor as needed for optimum performance.

William W. Casady
Department of Agricultural Engineering

Athletic field drainage

My teacher has given me a class project to find the best way to drain the track infield. The field is in kind of a "U" shape with a gradual slope to a storm drain. Over the years the soil has eroded and is uneven. There is often standing water in the infield. Maybe we could use underground drain tiles. What do you think?

To design a subsurface drainage system, we really need to know the soil type. For farmers' fields, a Natural Resources Conservation Service (NRCS) soil survey is usually available that shows the soil type.

Some Missouri soils are so "tight" that subsurface tile drainage is not feasible. With other soils, for agriculture, tile spacing may range from 20 feet to more than 150 feet apart. Common tile depths are 3 to 4 feet deep.

I assume that there has never been a soil survey that includes the athletic field site. Check with your local NRCS office to learn if they can identify your soil type. You might ask NRCS about sending someone to consult with you also on the erosion problem you mention. It may be more practical to solve the flooding problem with surface drainage instead of subsurface drainage.

Don Pfost
Associate Professor Emeritus
Food Science and Engineering

Frost line

What is the frost line in Central and Southern Missouri?

The 25-inch-deep frost line runs from the southwest corner of Bates County to the north St. Charles County line about through Jefferson City.

The 20-inch-deep frost line runs about straight from the southwest corner of Jasper County through the center of Jefferson County.

The 18-inch-deep frost line runs about straight from the southwest corner of Stone County through the center of Perry County.

The 15-inch-deep frost line runs about straight from the NE corner of Arkansas where the Bootheel juts south (near the southeast corner of Butler County) through the southern tip of Mississippi County.

Don Pfost
Associate Professor Emeritus
Food Science and Engineering

Updated 4/8/08