SU1711124A1 - Device for regulation of gas flow rate - Google Patents

Abstract

The invention relates to automation, in particular to devices for controlling the flow of gas, and may find application in analytical instrumentation. The purpose of the invention is to increase speed, accuracy and simplify the device. The device includes a housing 3 with an inlet 4 and an outlet 2 with nozzles connected by a channel 5 in which a heating thread 6 is placed coaxially. 9 provides movement of the shutter 7 in the direction of opening in the case of elongation of the heating filament 6 (while reducing the gas flow). The additional spring element 12 prevents the thread 6 from being pulled out in the absence of its heating current. 2 Il.

Description

This invention relates to the control of gas flow rates and may find application in analytical instrumentation.

The aim of the invention is to improve the speed, accuracy and simplification of the device.

Figure 1 shows the proposed device; figure 2 is a setting element.

The device has a cover 1 with an outlet nozzle 2 and a body 3 made of an electrically insulated material with an inlet nozzle 4 and a channel 5 connecting the inlet and outlet nozzles. A heating thread 6 is coaxially placed in the channel 5, which functions as a meter for the gas flow rate and simultaneously drives the shutter 7, which interacts with the saddle 8, which is fixed (ensuring tightness) on the housing 3 at the end, channel 5 coaxially with it. The shutter 7 and the saddle 8 are made of adhesive-resistant material, such as ruby stones GOST 7137-78. The shutter 7 is fixed

on the adjustment element 9, made in the form of a flat spring, which is installed in the bore of the housing 3 and fixed by a gasket 10 installed between the cover 1 and the housing 3. The adjustment element 9 moves the shutter 7 in the opening direction when the heating filament 6 lengthens due to its heating current from the power source 11. Between the setting element 9 and the shutter 7 an elastic element 12 is installed, made of rubber. The elastic element prevents the heating filament 6 from drawing out in the absence of its heating current, as well as when the device is transported under conditions of negative ambient temperatures.

The device works as follows.

A gas pressure is generated at the device inlet (nipple 4). At the initial moment with the power supply 11 turned off, the heating filament 6 has a length

to

corresponding to room temperature. The length of the heating filament is chosen experimentally so as to ensure the deformation of the elastic element 12, which is sufficient to completely seal the pair of saddle 8 -block.7. The force required to completely seal the pair of saddle 8 - shutter 7 made of ruby time stones; is 5-10 g and is achieved with a slight deformation of the elastic element 12 made of rubber.

When the power source 11 is turned on, the heating current flows through the heating filament 6. Thread 6 increases its length by an amount proportional to the current flowing through it. Under the action of the adjustment element 9 (spring), the shutter 7 is raised above the saddle 8 by a distance corresponding to the elongation of the thread 6. Through the gap between the saddle 8 and the shutter 7, the gas supplied to the channel 5 through the inlet 4 first flows into the volume between the lid 1 and body ZgE then to the outlet 2. The size of the parasitic volume between the output of the channel 5 and the outlet of 2 this flow regulator compared with the prototype is reduced by two orders of magnitude, and the parasitic volume between the exit of the channel and the locking body is excluded completely.

 When gas moves through channel 5, the amount of heat removed from the filament b increases, which leads to a decrease in its temperature and a decrease in its length. After 5-10 seconds, a heat balance is established between the temperature (length) of the filament 6 and the gas flow rate, i.e. the magnitude | of the gas flow rate becomes constant and corresponds to the magnitude of the output current (voltage) of the power source 11.

With an increase in the flow rate of gas flowing through the regulator, due to a change in the magnitude of the load at the outlet of the device or due to a change in the inlet pressure, the amount of heat taken from

filament 6. The temperature decreases and, consequently, decreases its length and the gap between the saddle 8 and the shutter 7, which leads to a decrease in gas consumption to previously

set value. Reducing the flow rate of the gas flowing through the regulator leads to a decrease in the amount of heat taken from the filament 6, and to an increase in its temperature and length, i.e. to

increase the gap and, accordingly, the gas consumption;

In this way, automatic maintenance of the gas flow rate is carried out. In the steady state, the time of transient processes with an increase or decrease in the gas flow rate is a fraction of a second, since even with a small gas flow (10 cm3 / min) the gas velocity in channel 5, whose diameter is 0.20, 3 mm, is rather high, and the shutter 7, located at the end of the housing 3 coaxially with the channel 5, due to the absence of volume between it and the output of the channel 5 provides inertialess synchronous change

the magnitude of the gas flow in accordance with the change in the length of the thread 6.

Claims (1)

Apparatus of the Invention A device for controlling a gas flow rate comprising a body made of an insulating material, in the channel of which a heating thread is installed between the inlet and outlet nozzles, one end of which is fixed in the body and the other end connected to the regulator associated with a tuning element, which, in order to increase its speed, accuracy and simplification, is made in the form of a flat spring, one end of which is fixed to the housing, the regulator is made in the form of a gate spring fixed on the other end, the seat of which is fixed on the end of the channel, and an elastic element is installed between the gate and the second end of the flat spring.