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Laundry Data Calculations

Cylinder Cubic Content

Cubic content measures the physical size of cylinder (or basket). It is the best way to compare rated capacity of competitive machines. The higher the cubic content, the more laundry the machine's cylinder can hold. It is calculated as follows:

(PI)R2 (radius of cylinder) x depth of cylinder / 1728 = cubic content of cylinder

The accepted capacity for washer-extractors is between 5 and 7 lb. per cubic foot
Accepted capacity for dryers is between 2.5 and 3.5 lb. per cubic foot.

Volume

Volume refers to the available area within the basket or cylinder of the washer. Here are some relationships between cubic content, gallons and liters.

1.0 cubic foot = 7.48 gallons = 28.27 liters
0.134 cubic foot = 1.0 gallons = 3.78 liters

G-Force

G-Force is a relative measurement used to compare a washer's extraction capabilities (spin cycle).  Comparatively, higher RPM's relate to higher G-Force when the cylinder size is similar.  However, larger diameter cylinders can spin slower, yet attain a higher G-Force than smaller diameter cylinders.  Here's the formula to calculate G-Force:

RPM2 x diameter (inches) / 70,500 = "G" Force

Water Data

Here's some specific data on water:

About 60% of water used in a typical laundry formula is hot (if a conventional water system is used).

1 cu. ft. of water = 62.425 lb. 1 cu. ft of water = 7.48 gallons
gallon(s) x .1336 = cubic feet gallon(s) x 231 = cubic inches
pound of water x .016 = cubic foot pound of water x .12 = gallons
1 gallon = 8.33 lb. @ 62 degrees Fahrenheit (
oF)

Boiling water = 212 Fahrenheit (ºF) = 100 Celsius (ºC)
Freezing water = 32 Fahrenheit (
ºF) = 0 Celsius (ºC)

To convert to ºF; multiply ºC by 9, divide by 5, and add 32.
To convert to
ºC; subtract ºF by 32, multiply by 5, and divide by 9.

Moisture Retention

Moisture retention measures the water extracted from the load. The more water removed from the load, the less drying time required. Too much water removal, however, can damage fabrics. A certain amount of water retention is required for finishing procedures. To calculate moisture retention, use the following formula:

Weight after extraction - dry weight / dry weight = Moisture Retention (%)

Water Hardness

More tallow soap is required for washing in hard water than in soft water. A water softener may be required if grains/gallon of hardness exceed 3.

Water Hardness definitions:

Grains/Gallon Parts/Million Description
less than 1.0 less than 17.1 soft
1.0 to 3.5 17.2 to 60 slightly hard
3.6 to 7.0 61 to 120 moderately hard
7.1 to 10.5 121 to 180 hard
10.6 & over 181 & over very hard

Electricity

    horsepower x .7457 = kW
    watt/hour x 3.413 = BTU
    1 kWh = 3413 BTU = 1 kW x number of hours operated

To calculate approximate electrical consumption, use the following formula for each motor in the laundry (then total the results for all motors):

U x I x 1.7321 x PF /1000 x # of hours operated per day = kW/day

where: U = voltage (volts); I = current (amps); PF = power factor

As a rule of thumb, assume motors are running under a constant load ? such as a washer-extractor motor at .80.

Gas Data

A BTU is the amount of heat required to raise one pound of water approximately one degree Fahrenheit (ºF):

> one Therm (TH) = 100,000 BTU
> one cubic foot = 1,000 BTU (approx..)
> one MCF (1,000 cubic feet) = 10 Therms (approx..)
> one cubic foot of Butane gas = 3,200 BTU
> one gallon No. 2 diesel fuel oil = 139,500 BTU (approx.)
> one gallon No. 6 fuel oil = 149,000 BTU (approx.)
> one kilowatt (kW) = 3,415 BTU
> one gallon propane = 92,000 BTU

Gas cost : The cost of gas is usually stated in the price per therm or price per M or MCF (1,000 cubic feet). In computing costs, the actual total to the end user should be used, and divided by the number of therms used to find the cost per therm. Various rate structures are used by local gas suppliers. These include "straight line" rates, and "block" rates in which the rate varies for various quantities. Additional charges such as "demand charge", "commodity charge", or "service charge" may also be part of the gas cost. Any charge the customer may pay to receive gas, including sales tax where applicable, should be included in the total gas cost from which the actual cost per therm is derived.

Boiler Horsepower

one BHP = the work of converting 34.5 lb. of water per hour from and at 212 ºF to steam at 0 lb. gauge pressure.

one BHP = 33,500 BTU/hr
one BHP = 34.5 lb./steam
one BHP = 9.803 kilowatts

Metric Equivalents

1 U.S. gallon = 3.785 liters
1 cubic foot = 0.028 cubic meters = 28.317liters
1 foot = 0.3048 meters
39.37 inches = 3.28 feet = 1.0 meters
1 pound= 0.4536 kilograms

         LAUNDRY WEIGHTS CHART

Item / Description

Weight (Grams)

Aprons 350
Bath Mat 450
Bath Towel 750
Bath Towel XL 1000
Bed Spreads 1500
Blankets - Honeycomb 1200
Blankets - Single 1200
Blankets - Double 1700
Hats / Caps 1500
Chef's Jackets 500
Chef's Trousers 500
Chef's Aprons 350
Draw Sheets - Cotton 375
Dust Coats - Pure Cotton 450
Dust Coats - Cotton 650
Duvet Covers- Single 1600
Duvet Covers - King Size 2500
Face Cloths 150
Face Towels 200
Hand Towels 350
Mops - Small 500
Mops - Large 200
Overalls - Mens Cotton 800
Overalls - Mens Pure Cotton 650
Overlays 400
Pillowcases 150
Quilts - Single 2000
Quilts - Double 4000
Serviettes 200
Sheets - Single Pure Cotton 450
Sheets - Double Pure Cotton 600
Sheets - Single Cotton 700
Sheets - Double Cotton 900
Sheets - King Size Cotton 1125
Table Cloths - Small 300
Table Cloths - Medium 500
Table Cloths - Large 700
Theatre Gowns - Cotton 650
Uniforms - Ladies Pure Cotton 400
Uniforms - Ladies Cotton 500

 


This information courtesy of Division of Building Technology, CSIR.


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