DE8217261U1 - Device for determining the foreign water content in milk - Google Patents

Description

Funke-Dr .N. Gerb'dr'GpbH '· ; ; - ·, _# '. "'. ' . * Anzinger Str. J _# ·. _F j ", * _r . · * ,. · ·,. ·.; ..

P.O. Box 80 06 26

άοοο chicken 80

Description of the freezing point determiner with self- -I active inoculation to determine the foreign water content in milk

The freezing point

All liquids have a certain temperature point - the so-called freezing point, at which they begin to crystallize and become frozen,

But now these liquids stand still and are not

'f; contaminated, you can find them under the respective genres

'The freezing point is supercooled and you are still in

liquid state. But is now in the. hypothermic

I liquid that has already been frozen milk (or water)

I leads - even if only in a minimal amount - or in the un-

If the chilled liquid is moved a little, it will kick in for a long time

I; due crystallization and a heat is released -

i the so-called heat of fusion. The liquid will then be on

', the temperature at which crystallization normally occurs - i.e. the freezing point.

When this process is finished, the colder ambient temperature of the cooling block is assumed.

The freezing point in milk:

With pure or distilled. Haters is this freezing point at 0,000 C - the so-called. Zero point. If this hater z. B. sodium chloride added, so this freezing point decreases depending on

■ Amount of the * sodium chloride supplied, e.g. B. at 9.421 g per

j liter to -o, 557 ° C.

! The freezing point of unadulterated milk is around -o.535 ° C.

'■ The addition of water increases the freezing point - df? „Er

shifts towards the zero point. This shift is equal to the hater addition - i.e. Io% temperature change

¹ equals Jo % added water.

_mm O _mm

The freezing point determination

The freezing point determiner with independent inoculation to determine the foreign water content in milk measures the freezing point.

The amount of liquid to be measured is 0.2 ml. It is filled into a sample container (12) with a pipette. The vessel with the liquid is cooled in the cooling block fi! The cooling block (1) receives its temperature of -Io C through the Peltier element (13) . The temperature of the liquid is measured by the two NTC resistors (2) and indicated as C as an electrical voltage on the digital voltmeter (14). When the liquid has reached -5 ° C, the drive pulley (9) is set in motion by an electric motor and the rod (10) moves the inoculation slide (7) up and down. The inoculation needle (5), which is also cooled in the cooling blockf1) and wetted with tiny ice crystals , is guided upwards; In the uppermost position of the inoculation slide (7), an electromagnetically driven pivoting of the inoculation needle (5) to the left is achieved by the switch (11) and the inoculation needle (S) is inserted into the sample vessel f12) by moving it downwards . Crystallization is triggered by immersing the ice crystals in the supercooled liquid. The rising temperature as well as the freezing point and the subsequent adjustment to the temperature of the cooling block (U is now measured by the NTC resistors (2)! In the form of resistance values sent to the electronic transducer / from this as an electrical voltage to the digital voltmeter (12) forwarded, where it is made digitally visible.

The user can now follow the temperature curve precisely and Compare the measured freezing point with the freezing point for unadulterated milk as a percentage and thus have the precise foreign water content of the milk.

-J-

Particularities:

In practice, the milk is examined by the producer a sample is drawn, which is usually 100 ml. Here but from this amount not only the freezing point is determined, But also other values, the sample amount of 2 ml is interesting, because with this small amount several tests can easily be carried out for a more precise determination.

Since the freezing point of unadulterated milk is -o.535 ° C, only half a degree Celsius is available to determine the foreign water. In order to measure as accurately as possible, it is necessary to measure 1 / looo C. In order to keep the tolerance of the NTC resistance as low as possible, two NTC resistors are connected in series in the freezing point determiner with automatic inoculation. So there is the possibility that the tolerances of the NTC resistors cancel each other out. This also means that the better condition of the liquid is measured.

So far, the sample vessel has been cooled with a cooling bath achieved, which required constant control of the liquid level as well as a movement of the cooling liquid. In the freezing point determiner with independent inoculation, the dry cooling with a release element achieves cooling of the sample vessel and is therefore maintenance-free.

The crystallization of the supercooled sample is done by an externally cooled Naidel, which is wetted with tiny ice crystals is triggered automatically at -5 ° C, · in contrast to other devices in which the needle is in the sample from the start and the crystallization is triggered by vibration. The triggering by supplying crystals corresponds more to the previous method.

Designation of the individual parts for FIG. I.

1 " Cooling block

2 β NTC resistance

3 = Thermistor socket

4th " Holder for thermistor socket

5 * Inoculation needle

6th = Guide bush

7th ** Vaccination sled

8th * Guide rod

9 * Drive pulley

10 *> Linkage

11th « Switch for rod swivel

12th = Sample vessel

13th * Peltier element

14th = Digital voltmeter

• r ι

Claims (4)

PROTECTION CLAIMS 1.) Device for determining the foreign water content in milk characterized in that a sample vessel made of plastic with a beaded rim and an upper one which tapers conically downwards at 18o degrees is used to examine o.2 ml of milk Internal diameter of 9 mm and a wall thickness of 0.8 mm and a length of 39 mm is provided. 2) Device for determining the foreign water content in milk, characterized according to claim 1, that the temperature measurement by a rod-shaped plastic socket with the Measures 3 mm diameter and 40 mm total length in the two glass probes with the dimensions 0.8 mm diameter and 12 mm length are cast, in each of which there is an NTC resistor cast into the glass probe 3) Device for determining the foreign water content in milk, characterized according to claim 1 and 2 that for the Milk cooling a card-shaped Peltier element (13) with the Dimensions 3o χ 3o χ 3 mm is arranged behind a rectangular cooling block (1) with the dimensions 45 χ 3o χ 2o mm. 4) Device for determining the foreign water content in milk, characterized according to claims 1-3, that a 46 mm long inoculation needle (5) with a diameter of 1 mm is arranged vertically movable in the cooling block cooled by the Peltier element for the crystallization of the milk sample . Il IMI