Select Page

# Handy Formulas

## Determining what size of washers you need in your laundry

Washer size requirements are determined by several primary factors including space available, volume of linen and hours to process.

How many pounds of linen do you process each day and how many shifts do you want to do it in. Hospitality linens can be loaded, washed and unloaded in 45 minutes or less depending on the length of the wash program and whether or not ozone is used. Programs with ozone are markedly shorter than traditional programs. This means that you will get 1.25 loads or more out of a washer every hour. Healthcare linen programs are typically 1/3 longer than hospitality linen wash programs. This data and other location specific information like what rate does the linen come into the laundry (health clubs get a trickle of towels all day long) and how much space do you have in your laundry room are used to determine what size of washer and how many you need.

Example –

Hospitality (10,000 lbs. / two 8 hour shifts)
10,000 lbs. divided by 16 hours = 625 lbs per hour
4 / 135 lbs. washers = 540 lbs x 1.25 = 675 lbs / hr. x 16 hrs. =
10,800 lbs.

Healthcare (10,000 lbs. / two 8 hour shifts)
10,000 lbs. divided by 16 hours = 625 lbs. / hr.
5/ 135 lbs. washers = 675 x 1: 1 = 675 lbs / hr. x 16 hours =
10,800 lbs.

## Other Calculations

### Calculating Cylinder Volume

Cylinder Diameter and Cylinder Depth are both expressed in inches.

Cylinder volume in cubic feet =

(Cylinder Diameter) x (Cylinder Diameter) x (Cylinder Depth)
2,200

### Calculating extract ‘G’ Force

Extract G-force is a way of comparing washers with different cylinder sizes and extract speeds. Always ignore RPM’s and compare G-Forces. To calculate G-Force, use this formula:

RPM is cylinder rotation speed in revolutions per minute. Cylinder diameter is expressed in inches.

G’s =

(RPM) x (RPM) x (Cylinder Diameter)
70,500

### Moisture content after extraction

Moisture content is a way of expressing how much water remains in a load of linens after extraction. This is water that must be removed by turning into steam in a drying tumbler or ironer. To calculate moisture content, use this formula:

WAE = weight of load after extraction, in pounds
DRY = weight of load before washing, in pounds

% Moisture Content =

(WAE) – (DRY) x 100
(DRY)

Example: A load of linens weighs 60 pounds before processing. After washing and extracting, the load weighs 90 pounds. The % moisture content would then be:

% Moisture Content =

 (90 – 60) x 100 60 = 50%