K-factor
From Wikipedia, the free encyclopedia
Contents |
[edit] Telecommunications
In telecommunication, the term k-factor has the following meanings:
1. In tropospheric radio propagation, the ratio of the effective Earth radius to the actual Earth radius.
Note: The k-factor is approximately 4/3.
2. In ionospheric radio propagation, a correction factor that (a) is applied in calculations related to curved layers, and (b) is a function of distance and the real height of ionospheric reflection.
3. In laser diode technology, it describes the exceed spontaneous emission noise in gain-guided lasers.
Source: From Federal Standard 1037C and from MIL-STD-188
[edit] Fire protection engineering
In Fire protection engineering, the term k-factor has the following meaning:
The flow rate of a sprinkler is given by 
. Where p is the operating pressure, usually given in bar. K is the K-factor commonly given in units of 
.
The units conveniently allow 
to stand for either the mass flow rate in kg/min or the volumetric flow rate in L/min.
It is a factor to find the effective length of the column in structural engineering.
[edit] Sheet metal engineering
In Sheet metal engineering, the term k-factor has the following meaning:
During bending the inner surface of the bend is subjected to compression while the outer surface is subjected to tension. However there is a layer in between which is free from any forces and thus its length remains the same. This is called the neutral axis ( N.A ). The radius of this layer of metal is called the neutral bend arc radius ( NBAR )and is defined as the inside bend radius plus a percentage( K-factor ) of the metal thickness.
NBAR = BR + (T * K-factor)
The K-Factor ( K ) depends on the material, the type of bending operation (coining, air-bending), the ratio of the Bend Radius to the metal thickness ( R/T ) and is typically between 0.3 to 0.5. For most types of steels it is around 0.33 to 0.4
[edit] Insurance
In actuarial work, the term K-factor refers to the ratio of deferrable expenses to the Estimated Gross Profits. It is an important measurement used to manage the deferrals allowed in insurance accounting.
[edit] Oil heating
[edit] Degree day system
The degree day system is based on the amount of fuel a customer has consumed between two or more deliveries and the high and low outdoor temperatures during the same period. A degree day is defined as one degree of temperature below 65°F in the average temperature of one day. In other words, to arrive at the number of degree days in one day, the official high and low temperatures for that day must be obtained. The two figures are then averaged, and the number of units this average is below 65°F is the number of degree days for that day. For example, if for Tuesday, November 3, the high temperature is 70°F and the low is 54°F, the average is found by adding 70 and 54, which equals 124, and then dividing by 2. The resultant figure is 62, and by subtracting 62 from 65, it is determined that there were three (3) degree days that day.
[edit] K-Factor
To determine usage or "K" factor, first compute the number of gallons of fuel oil used in a given period. Then, using the cumulative total of degree days for the same period of time, you can figure the "K" factor, or the number of degree days that one gallon of fuel will last at the current rate of consumption. This factor is arrived at by dividing the number of degree days in any given period by the total number of gallons of fuel consumed during the same period. For example, if during the month of November your furnace burns 200 gallons of fuel oil and assuming that we had 300 degree days, your "K" factor would be 300 divided by 200, which equals 1.5. In other words, each gallon of fuel oil provides you with 11/2 degree days of heat.
The next step is to determine how many days' supply remain in the tank once it has been filled. From the total tank capacity, you can subtract a number of reserve gallons which depends, of course, upon the size of the tank. Then multiply the number of gallons of usable fuel by the "K" factor, and you have what is known as the Degree Days of Usable Fuel. Using this figure, oil companies can arrive at the degree day of your next scheduled delivery.
[edit] Physics
The term k-Factor is sometimes used to express the thermal conductivity of a material, that is the property of a material that indicates its ability to conduct heat.
