Dictionary

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D-Bar

A bar located on the underside of the winder. Used for sheet spreading to keep rolls from running together on the winder. Common name is spreader bar.

D.C. Motor

Motor driven by direct current.

Damp Streaks

Crushed or blackened streaks running in the machine direction. They are the result of crushing caused during pressing or calendering a sheet of paper having high moisture content areas.

Dandy "Pick"

A defect in paper caused by the dandy roll picking up fibers from the sheet or otherwise disturbing the sheet formation to leave thin spots or other imperfections.

Dandy Roll

(1) A roll placed on the fourdrinier to help reduce two sidedness of the sheet. (2) A skeleton cylinder covered with a woven wire cloth, or with an arrangement of fine longitudinal wires, crossed at close intervals by heavier circumferential wires. The former structure produces wove and the latter laid paper. The dandy roll is one method of applying watermarks to paper while wet. It is positioned on the top of the wire in front of the couch roll.

Data Processing

The accumulation and storage of mill data in the mill's computer system.

Deckle

(1) A term indicating the width of the web formed on the paper machine. (2) The straps (deckle ruler) on the wet end of a paper machine which prevent the fibers from flowing over the sides and which determine the width of the web of paper which can be run on any given machine.

Decor Paper

Special papers for laminating chipboard surfaces in the furniture and construction industry. Décor paper is rotogravure color printed with a wide range of imitation wood graining, masonry textures or other patterns. Later the paper is impregnated with resin and pressed onto the chipboard surface.

Defoamer

A surface-active chemical used to inhibit the production of and to kill foam.

Demineralizer

A vessel which utilizes an ion exchange resin to chemically remove scale and sludge forming material from boiler feed water.

Density

The weight per unit volume of a material, i.e., water has a weight of 8.33 Ibs./gallon, etc.

Department

The units of division within the mill. Each is the responsibility of the designated department head.

Desuperheating Water

Water introduced into a steam line to lower the superheat temperature and which reduces steam pressure.

Differential

The difference in pressure between the inlet dryer steam pressure and the outlet condensate pressure, or the difference in pressure from the top dryers to the bottom dryers.

Digester And Blow Digester

"Large pressure vessel in which wood chips are cooked to separate fibers from each other and from undesirable particles in the wood. To ""blow the digester"" means to release the pressure and empty the contents of the digester."

Digital Hardware Station (Dhsplus 6)

The Digital Hardware Station manages the flow through the digital valve blocks. Setpoints are sent from the Integrated Process Station using measurement system data.

Digital Valve Block

The digital valve is used to control the amount of water of each control zone. Each valve block has 6 solenoids. With the combination of the setpoints for the solenoids the water flow is controlled in 64 steps from minimum to maximum flow.

Dilution

The addition of water to lower concentration.

Dimensional Stability

That property of a sheet of paper which relates to the constancy of the dimensions in the machine and cross-machine directions under conditions of different relative humidity.

Direct Process Paper

A fine paper especially designed for treatment with a light-sensitive coating. This paper then becomes the copy paper for diazo reproductions, such as Ozalid. The master for producing these copies can be on Nekoosa Master-Lucent.