TIP 0404-07
OLD TIP NO. 014- 17
ISSUED – 1970
REVISED – 1984
REVISED – 1989
REVISED – 1991
REVISED – 1994
REVISED – 2000
REVISED – 2004
REVISED - 2005
© 2005 TAPPI
The information and data contained in this document were prepared by
a technical committee of the Association. The committee and the
Association assume no liability or responsibility in connection with the
use of such information or data, including but not limited to any
liability or responsibility under patent, copyright, or trade secret laws.
The user is responsible for determining that this document is the most
recent edition published.
TIP Category: Automatically Periodically Reviewed (Five-year review)
TAPPI
Paper machine drying rate
Scope
This TIP outlines procedures for calculating paper machine drying rates for coated and uncoated papers and
provides drying rate curves. The objective of the TIP is to define rate of water removal on a common basis for mills
to use to compare a particular machine to past performance and to other machines. The definition of drying rate and
its calculation are simple to permit widespread use. These procedures cannot be used for machines with auxiliary
drying equipment such as infrared dryers and impingement dryers unless these auxiliary dryers are shut off.
Data points on the curves represent observed performance of existing machines. Lines represent calculated
average and two-sigma variation of plotted data.
The calculation does not identify or account for factors that affect drying rate. There are many variables that
can affect calculated drying rate. These factors include:
• Sheet furnish
• Dryer configuration
• Type of pressing
• Syphon design
• Dryer felting
• Amount of pressing
• Use of dryer bars
• Dryer surface scale
• Breaker stack
• Pocket ventilation
• Hood humidity
• Dryer fabric application
• Reel moisture content
Safety precautions
This TIP outlines a calculation procedure. No safety precautions are required.
Definition of drying rate
The drying rate (R
W
) as applied to drying on the machine is defined as the amount of water evaporated per
hour per unit area of drying surface. Drying surface is defined as the total circumferential length of steam-heated
dryers that are in contact with the sheet multiplied by the width of the sheet at the reel. Drying rate is expressed as
pounds per hour per square foot in customary units and as kilograms per hour per square meter in SI units, and
reported at the average steam temperature.