Flow control and measurement through particle counters

Patent metadata

Field	Value
Publication number	US-2023366709-A1
Application number	US-202118028608-A
Country	US
Kind code	A1
Filing date	Sep 27, 2021
Priority date	Sep 28, 2020
Publication date	Nov 16, 2023
Grant date	—

Abstract

Disclosed herein are systems and methods for measuring and controlling a flow rate through a particle counter or active air sampler. As disclosed herein, a fluid flows through a venturi tube and an orifice in the system at a predetermine velocity. A pressure differential between an inlet of the instrument and a throat section of the venturi tube is measured. The flow rate through the system can be determined based on the pressure differential and an intensive property of the fluid. An alarm can be activated when the flow rate is outside of a flow rate range.

First claim

What is claimed is:

1 . A method for generating a flow and measuring a flow rate of the flow through an instrument, the method comprising:
creating a vacuum downstream of a venturi tube and an orifice downstream of the venturi tube to draw a fluid through the venturi tube, the orifice, and the instrument at a predetermined velocity; measuring a pressure differential between an inlet of the instrument and a throat section of the venturi tube; determining the flow rate through the instrument based on the pressure differential and an intensive property of the fluid; and setting a flag when the flow rate is outside of a flow rate range.

2 . The method of claim 1 , wherein creating the vacuum to draw the fluid through the venturi tube and the orifice at the predetermine velocity includes creating the vacuum using an external vacuum source to draw the fluid through the venturi tube and the orifice at a sonic velocity.

3 . The method of claim 1 , wherein creating the vacuum comprises creating the vacuum such that a pressure downstream of the venturi tube and the orifice is less than or equal to about 52% of a pressure at the inlet of the instrument.

4 . The method of claim 1 , wherein the flow rate is a volumetric flow rate.

5 . The method of claim 1 , further comprising measuring an ambient pressure exterior to the instrument.

6 . The method of claim 5 , further comprising detecting an obstruction upstream of the instrument based on the ambient pressure and the flow rate.

7 . The method of claim 1 , wherein measuring the pressure differential comprises measuring the pressure differential with a differential pressure transducer.

8 . The method of claim 1 , wherein measuring the pressure differential comprises:
measuring a first pressure at the inlet of the instrument; measuring a second pressure at the throat section of the venturi tube; and calculating the pressure differential using the first pressure and the second pressure.

9 . The method of claim 1 , wherein the instrument is an active air sampler.

10 . The method of claim 1 , wherein the instrument is a particle counter.

11 . A method for controlling a flow rate of a fluid through a system including an instrument, the method comprising:
activating a pump to cause the fluid to flow through the system; measuring a pressure differential between an inlet of the instrument and a throat section of a venturi tube; determining the flow rate through the particle counter based on the first pressure, the second pressure, and an intensive property of the fluid; and adjusting the pump to increase or decrease the flow rate when the flow rate is outside of a flow rate range.

12 . The method of claim 11 , further comprising measuring an ambient pressure exterior to the instrument.

13 . The method of claim 11 , further comprising:
detecting an obstruction upstream of the instrument based on the ambient pressure and the flow rate; and activating a first alarm upon detecting the obstruction.

14 . The method of claim 11 , wherein the flow rate is a volumetric flow rate.

15 . The method of claim 11 , wherein
the pump is a vacuum pump; the system includes an orifice located downstream of the venturi tube; and activating the pump to cause the fluid to flow through the system includes activating the vacuum pump create a vacuum in the system to draw the fluid through the system and the orifice at a sonic velocity.

16 . The method of claim 15 , wherein activating the vacuum pump to create the vacuum comprises creating the vacuum such that a pressure downstream of the venturi tube and the orifice is less than or equal to about 52% of a pressure at the inlet of the instrument.

17 . The method of claim 11 , wherein measuring the pressure differential comprises measuring the pressure differential with a differential pressure transducer.

18 . The method of claim 11 , wherein measuring the pressure differential comprises:
measuring a first pressure at the inlet of the instrument; measuring a second pressure at the throat section of the venturi tube; and calculating the pressure differential using the first pressure and the second pressure.

19 . The method of claim 11 , wherein the instrument is an active air sampler.

20 . The method of claim 11 , wherein the instrument is a particle counter.

21 . A system for measuring a flow rate of a fluid through an instrument, the system comprising:
a venturi tube having an inlet, an exit, and a throat located between the inlet and the exit; a differential pressure transducer operative to sense a pressure differential between the throat and a point upstream of the inlet of the venturi tube; a controller in electrical communication with the differential pressure transducer and operative to perform actions comprising:
converting a first signal from the differential pressure transducer to the pressure differential,
determining the flow rate through the instrument based on the pressure differential and an intensive property of the fluid, and
setting a flag when the flow rate is outside a flow rate range.

22 . The system of claim 21 , further comprising a pressure transducer in electrical communication with the controller, the controller operative to perform additional actions comprising:
converting a signal from the pressure transducer into an ambient pressure measurement; and detecting an obstruction upstream of the venturi tube based on the ambient pressure and the flow rate.

23 . The system of claim 21 , further comprising:
an orifice located downstream of the exit, the orifice sized such that upon application of a vacuum, the fluid flows through the system at a sonic velocity; and a vacuum source in fluid communication with the orifice, the vacuum source operative to draw the fluid through the orifice at the sonic velocity.

24 . The system of claim 21 , wherein the flow rate is a volumetric flow rate.

25 . The system of claim 21 , further comprising a blower downstream of the venturi tube, the controller configured to transmit a fourth signal to the blower, the fourth signal operative to adjust a blower speed.

26 . The system of claim 21 , further comprising a third pressure transducer in electrical communication with the controller, the controller operative to perform additional actions comprising:
converting a signal from a third pressure transducer into an ambient pressure measurement; and detecting an obstruction upstream of the venturi tube based on the ambient pressure and the flow rate.

27 . The system of claim 21 , further comprising the instrument in fluid communication with the inlet of the venturi tube.

28 . The system of claim 27 , wherein the instrument is an active air sampler located exterior to a housing of the system.

29 . The system of claim 27 , wherein the instrument is a particle counter located within a housing of the system.

30 . The system of claim 21 , further comprising:
an adjustable valve located downstream of the exit and in electrical communication with the controller; and a vacuum source in fluid communication with the adjustable valve, the vacuum source operative to draw the fluid through the adjustable valve, wherein the controller is operative to perform additional actions comprising adjusting an opening of the adju

Assignees

• Tsi Inc

Inventors

• Bayazit Yilmaz
• Anderson Tyler
• Remiarz Richard J

Classifications

• G01F1/42

  Orifices or nozzles · CPC title

• G01F1/44 Primary

  Venturi tubes · CPC title

• G01N1/24 Primary

  Suction devices {(G01N1/22 - G01N1/2294 take precedence)} · CPC title

• G01F1/363

  with electrical or electro-mechanical indication (G01F1/37 and G01F1/38 take precedence) · CPC title

• G01N1/2273

  Atmospheric sampling · CPC title