JPH02176444A - Ventilation resistance measuring device - Google Patents

Abstract

PURPOSE:To measure specimens having the different standards, sizes and the like continuously by communicating a first surge tank whose pressure is adjusted and second surge tank whose pressure is adjusted to the lowest pressure so as to hold the specimen to the sucking port of a specimen holder through a three-way valve. CONSTITUTION:A needle valve 20 is adjusted, and the pressure in a vacuum gage 22 is made to be a specified pressure. Then, a valve 37 is adjusted, and the pressure in a vacuum gage 25 is made to be the specified pressure. Then, a three-way valve 24 is turned ON, and a main sucking path 26 and a sucking path 23 are communicated. A valve 29 is adjusted, and the pressure in the gage 25 is made to be 200-300Torr. A specimen S is inserted through a specimen inserting port 11. The three-way valve 24 is turned OFF, and a pipe 36 and the sucking path 23 are communicated. The pressure in a holder A is made to be the pressure in a second surge tank 35, i.e. 700Torr. In this way, a latex tube 13 is brought into close contact with the specimen S so that the inner swelling amount at a part where the specimen S is not present is made small. Thus the specimens having the different sizes can be continuously measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in an airflow resistance measuring device for measuring airflow resistance of a sample such as a filter used for cigarettes.

[Prior Art] As shown in FIG. 4, a conventional ventilation resistance measuring device has a flange 3 near both ends of the outer peripheral surface of an inner cylinder 2 having a plurality of small suction holes 1, The inner peripheral surface of the outer cylinder 4 is airtightly fitted to form a double cylinder.

The outer cylinder 4 has a suction port 5 that opens to the outside, and an upper flange 6 and a lower flange 7 are provided at both upper and lower ends of the outer peripheral surface, and a hole is formed in the center of the upper flange 6 with a rubber gasket 8 in between. An upper holder 10 having a specimen insertion opening 11 is assembled to the lower flange 7, and a lower holder 12 having a specimen insertion opening 11 is assembled to the lower flange 7.
is assembled.

A latex tube 13 is coated on the inner circumferential surface of the inner tube 2, and both ends of the latex tube 13 are folded outward and fixed to both ends of the outer circumferential surface of the inner tube 2 to form a sample holder that accommodates the specimen inside. A is constructed.

The latex tube 13 has elasticity, and when the inside 14 of the double tube made up of the inner tube 2 and the outer tube 4 becomes vacuum pressure, the latex tube 13 comes into close contact with the inner peripheral surface of the inner tube 2, and the double tube When the internal pressure increases, the latex tube 13 bulges inward.

The hole 9 of the upper holder 10 is connected to a digital manometer 16 through a main measurement flow path 15, and the branch pipe 17 of the main measurement flow path 15 is connected to a first surge tank 21 through a filter 18, a flow rate controller 19, and a needle valve 20. It goes through.

Reference numeral 22 is a vacuum gauge that indicates the pressure in the branch pipe 17.

A latex tube suction path 23 connected to the suction port 5 is connected to a three-way valve 24.

Note that the reference numeral 25 is a vacuum gauge that indicates the pressure in the latex tube suction path 23.

The three-way valve 24 is connected to the latex tube main suction path 26 and the latex tube atmospheric pressure introduction path 27, and is connected to the control section 28.
When the command from turns ON, latex tube suction path 2
3 is connected to the latex tube main suction path 26, and when the command is turned OFF, the latex tube suction path 23 is connected to the latex tube atmospheric pressure introduction path 27.

The latex tube main suction path 26 has a needle valve 29
It communicates with the first surge tank 21 via.

The first surge tank 21 is provided with a pipe line 32 that is connected to a pipe line 30 that opens to the atmosphere and that is connected to a valve 31 that opens and closes according to commands from the control unit 28. Road 34 is connected.

To measure the ventilation resistance of a rod-shaped specimen S such as a filter plug using the ventilation resistance measuring device configured as described above,
First, the pressure in the first surge tank 21 is set to 200 to 300.
When adjusted to about TORR and the three-way valve 24 is turned on, the latex main suction path 26 and the latex tube suction path 23 communicate with each other, and the latex tube 13 comes into close contact with the inner circumferential surface of the inner cylinder 2.

Next, when the specimen S is inserted into the latex tube 13 and the three-way valve 24 is turned off, the latex tube suction path 23 is communicated with the latex tube atmospheric pressure introduction path 27, and the latex tube 13 receives atmospheric pressure. It bulges inward and tightly holds the outer peripheral surface of the specimen S.

Next, the needle valve 20 is opened to create a negative pressure inside the upper holder 10, and a constant flow of air is caused to pass through the sample S from the sample insertion port 11 and flow into the main measurement channel 15.
The ventilation resistance of the specimen S is measured by measuring the differential pressure between the sample S and the atmosphere using the digital manometer 16.

[Problem to be solved by the invention]

When the three-way valve 24 is turned OFF, the suction port 5 is set to atmospheric pressure, and the latex tube 13 is expanded inward to airtightly hold the outer circumferential surface of the specimen S, as shown in FIG. In the upper part, the inner bulge of the latex tube 13 becomes large, and the main measurement flow path is narrowed, causing a problem that accurate ventilation resistance measurement cannot be performed.

To counter this, we had to change the length of the sample holder depending on the length of the sample, or use sample holders with different inner diameters depending on the diameter of the sample, so it was necessary to prepare several types of latex tubes. In addition, the work of replacing the holder was complicated.

The present invention has been made to solve this problem.

[Means to solve the problem]

In order to achieve the above purpose, the inner peripheral surface of the inner cylinder of a double cylinder consisting of an inner cylinder and an outer cylinder having small suction holes is covered with a latex tube, and the double cylinder is kept under a predetermined negative pressure. When the latex tube is in close contact with the inner cylinder,
In the aeration resistor having a sample holder in which the latex tube swells inward to tightly hold the sample when the pressure exceeds a predetermined pressure, the first surge tank is adjusted to the negative pressure or less and the sample is airtightly held. A second surge tank adjusted to approximately the lowest pressure in the possible pressure range was communicated with the suction port of the sample holder via a three-way valve.

[Function] When the three-way valve is switched to communicate the second surge tank and the suction port of the sample holder, the latex tube swells inward and holds the sample airtight, but the pressure of the second surge tank holds the sample. Since the pressure is adjusted to approximately the lowest pressure in the pressure range that can be held airtight, the amount of inward expansion of the latex tube is small and the latex tube does not impede the flow of air passing through the specimen.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

Note that the same parts as in the conventional example are given the same reference numerals.

FIG. 1 is a system diagram showing the relationship between the various devices constituting the ventilation resistance measuring device. In place of the conventional latex tube atmosphere introduction path 27 connected to the three-way valve 24, a pipe communicating with the second surge tank 35 is used. Connect line 36.

The second surge tank 35 has a conduit 39 that connects to an atmospheric pressure introduction path 38 via a needle valve 37, and the conduit 39 connects to a conduit 41 that communicates with a vacuum pump 40.

The rest is the same as the conventional example.

Next, the ventilation resistance measurement of the specimen S using the ventilation resistance measuring device configured as above will be explained based on the flowchart of FIG. 3.

Turn on the power of the control unit 28 (So).

The valve 31 is closed by a command from the control unit 28 (
S.).

Next, the three-way valve 24 is turned off by a command from the control unit 28, and the suction port 5 of the sample holder A is communicated with the second surge tank 35 via the latex tube suction path 23 and the conduit 36 (S2).

The vacuum pump 33 is operated to lower the pressure in the first surge tank 21 (Sff).

Next, the vacuum pump 40 is operated to open the second surge tank 35.
(S4).

Open the needle valve 20 and adjust its opening degree to adjust the pressure displayed on the vacuum gauge 22 to a predetermined vacuum pressure (S,)
.

Next, after adjusting the display pressure of the vacuum gauge 25 to a predetermined pressure (700 TORR) by adjusting the opening degree of the needle valve 37 (S6), the three-way valve 24 is turned on to connect the latex tube main suction path 26 and the latex tube. Suction path 23
S7), adjust the opening degree of the needle valve 29 to adjust the pressure indicated on the vacuum gauge 25 to 200 to 300 TORR.
(S8).

The above pressure is transmitted to the latex tube 13 through the suction port 5 and the small suction hole 1, and the latex tube 13 is brought into close contact with the inner peripheral surface of the inner cylinder 2, and the latex tube 1
The inner diameter of No. 3 is enlarged to be larger than the diameter of the specimen S, and the specimen S can be inserted therein.

Next, after inserting the sample S from the sample insertion hole 11 (S,), turning off the three-way valve 24 (S,...), the pipe line 36
and the latex tube suction path 23 communicate with each other, so that the pressure inside the sample holder A gradually reaches the pressure of the second surge tank 7
It becomes 00TORR.

This pressure, as shown in FIG.
This is the pressure that reduces the amount of inward expansion of the latex tube 13 (at the upper part of the specimen S), and does not interfere with the measurement of the ventilation resistance of the specimen S.

Air passes through the sample S from the sample insertion port 11, flows toward the hole 9 of the upper holder 10, and then flows through the filter 18. It flows into the first surge tank 21 via the flow rate controller 19 and the two-door exchanger 20.

The flow rate of this air is limited to a constant amount by a flow rate controller 19, and the ventilation resistance of the sample S can be measured by a digital manometer that measures the differential pressure with the atmosphere.

After turning off the three-way valve 24 (sho) and after a certain period of time has elapsed (Sz), read the indicated value on the digital manometer (S+□).

When the measurement of ventilation resistance is completed, the three-way valve 24 is turned on to communicate the suction port 5 of the sample holder A with the first surge tank 21 (S, ff), and the latex tube 13 is brought into close contact with the inner surface of the inner cylinder 2.

Next, the sample S is taken out from the sample holder A, and the measurement of the sample S is completed (S, , ).

When a predetermined number of measurements are completed (S, S), the power to the control unit 28 is turned off (S16).

〔Effect of the invention〕

Since the present invention is configured as described above, the inward bulge of the latex tube that airtightly holds the specimen is reduced, making it possible to accurately measure specimens with different lengths and diameters. .

This eliminates the need for troublesome preparations such as changing the length of the sample holder depending on the length of the sample or changing the diameter of the sample holder depending on the diameter of the sample, which was required in the past. It has become possible to continuously measure several types of specimens with different values.

[Brief explanation of the drawing]

1 to 3 show embodiments of the present invention, in which FIG. 1 is a system diagram of equipment constituting the ventilation resistance measuring device, FIG. 2 is a vertical cross-sectional view of the sample holder, and FIG. 3 is a flowchart. FIG. 4 is a system diagram of the components of a conventional ventilation resistance measuring instrument, and FIG. 5 is a longitudinal sectional view of a sample holder in the conventional example. A... Sample holder, S... Sample, 1... Small hole for suction, 2... Inner cylinder, 4... Outer cylinder, 5... Suction port,
9... Hole, 11... Sample insertion port, 13... Latex tube, 15... Main measurement channel, 16... Manometer 19... Flow rate controller, 20... Needle valve, 21... First surge tank, 22... Vacuum gauge, 23... Latex control section, 29... Needle valve, 31... Valve, 33... Vacuum pump, 35... Second Surge tank, 37... Needle valve, 40... Vacuum pump.

Claims (1)

[Claims] When the inner peripheral surface of the inner cylinder of a double cylinder consisting of an inner cylinder with a small suction hole and an outer cylinder with a suction port is covered with a latex tube, and the double cylinder is brought under a predetermined negative pressure or less, In the aeration resistance measuring instrument having a sample holder, the latex tube closely contacts the inner cylinder to allow insertion of the sample, and the latex tube expands inward to tightly hold the sample at a predetermined pressure or higher; A first surge tank adjusted to a negative pressure or lower and a second surge tank adjusted to approximately the lowest pressure in a pressure range that can airtightly hold a specimen are communicated with the suction port of the sample holder via a three-way valve. An airflow resistance measuring instrument characterized by: