NO165464B - MEASUREMENT AND AIR DISTRIBUTION DEVICE FOR INTRODUCING INCOMING AIR IN A ROOM. - Google Patents

Abstract

A method of introducing supply air into a lower portion of a room space (3) directly to an occupied zone (7) by means of at least one elongated air distribution means (1) provided with a plurality of outflow openings (2) for supply air. In order to blow supply air into the occupied zone without draught and without drawing impurities from the upper portion of the room space, supply air is blown from the air distribution means at a high speed but through outflow openings so small that the speed of the air jets (A) from the openings is reduced essentially over a short distance (X) and the entrance of secondary air (B) from the room space into the air jets is prevented in the vertical direction of the room space over said distance (X) and at least at one end of the air distribution means. The air distribution means (1) is provided with a plurality of small outflow openings (2) the distance of which from each other in the longitudinal direction of the air distribution means is great as compared with the size of the outflow opening for enabling secondary air to flow from the room space in between the outflow openings, and to mix with the air jets from all sides.

Description

Process for the production of decay-

resistant roofing felt resp. rag- or

cloth cardboard resp. wool felt cardboard.

The present invention relates to a method for the production of rot-resistant roofing felt resp. rag or cloth cardboard resp. wool fit cardboard.

It has been known for a long time and there are numerous works that deal with the fact that you can add bactericidal agents to the fiber suspension before the cardboard is made, thereby giving the finished cardboard a rot-resistant finish. It was e.g. made investigations regarding the addition of pentachlorophenol sodium to the fiber suspension. During these investigations, it was established that pentachlorophenol, which is precipitated in the acidic area below pH 6, is not completely deposited on the fibres, but only approx. 50-60% is retained by the filter effect. This method for rot-resistant treatment of raw cardboard is difficult to put into practice, because the waste water contains a relatively large amount of the bactericidal agent, and cannot be easily discharged from the factory;

with the rot-resistant treatment of the raw cardboard known in the literature, a special treatment of the waste water must therefore be carried out, whereby the manufacturing costs of the rot-resistant cardboard are increased to a not inconsiderable extent.

With regard to the use of sodium pentachlorophenol, reference should be made to the publication Casey, Pulp and Paper, Volume 1, 1952,

p. 687, and French patent 1,119,356.

Furthermore, it is already known that aluminum sulphate or alum can be added to the fiber suspension before cardboard production. Such addition of alum or aluminum sulphate lowers the pH value of the fiber suspension. There are a large number of works which deal with the use in the paper industry of aluminum sulphate, respectively the sodium aluminate which is formed by addition. Likewise, an addition of sodium aluminate as such is known; - by adding sodium aluminate, a paper with a neutral reaction is mainly produced while maintaining the adhesive strength and, secondly, the retention of fillers and fibers is improved.

It now turned out in a surprising way that one can achieve, not only a utilization of 50-70% of the bactericidal agents, in particular pentachlorophenol sodium, on the fibers, but also a significantly higher adsorption, which can be over 90% , when the pH value of the fiber suspension is set to a fairly specific value after the addition of the bactericidal agent.

In accordance with the foregoing, the method according to the invention consists in the production of raw roofing cardboard, rag or rag cardboard or wool felt cardboard, in which pentachlorophenol sodium is added to the raw material suspension as an agent to kill micro-organisms, while in connection with this, the suspension is set to a pH value below 6 with the addition of aluminum sulphate, and the characteristic of the method is that the pH value is set to 4.2 to 4.8, whereby a heat-resistant complex compound is formed between the pentachlorophenol and aluminium. Preferably, the pH value is set to approx. 4.5.

Pentachlorophenol sodium is preferably added in an amount of around 1% based on the raw material.

As a further advantage of the method according to the present invention, it has surprisingly been shown that the use of the pH range according to the invention not only leads to a maximum utilization of the bactericidal agent, but also to a surprisingly high homogeneity in the finished cardboard. This can presumably be traced back to the fact that at a pH value of around 4.5, the isoelectric point of the components in the tissue board is reached, whereby a particularly homogeneous distribution and arrangement of the tissue fibers is achieved.

Example

Before being fed to the paper machine, the fiber suspension was first added in an amount of 1% pentachlorophenol sodium based on the raw material. The pH value of the fiber suspension was then adjusted to a pH value of 4.5 +0.2 by adding alum. To achieve this, it is generally necessary to add about 0.6 to 1.0 g of alum per liter of suspension. The fiber suspension which had been treated in this way was then fed to the paper machine

o o o o 2 and a raw cardboard with a weight of 450 g/m was produced in the usual way. An analysis showed that around 93% of the added pentachlorophenol had been retained in the cardboard, while only around 7% of the pentachlorophenol used was detected in the waste water (closed system). The concentration of pentachlorophenol in the waste water is below 0.2 mg/litre and consequently below the limit of concern; the waste water can be directed away without further treatment.

Claims (2)

Procedure for the production of raw roofing cardboard, rag or cloth raw cardboard resp. wool felt cardboard, in which pentachlorophenol sodium is added to the raw material suspension as an agent to kill micro-organisms, while in connection with this the suspension is adjusted to a pH value below 6 with the addition of aluminum sulphate, characterized in that the pH value is adjusted to 4.2 to 4.8 , whereby a heat-resistant complex compound is formed between the pentachlorophenol and aluminium. 2. Method according to claim 1, characterized in that sodium pentachlorophenol is used in an amount of about 1% based on the raw material.