Measuring instrument and method for detecting the content of oil, hydrocarbons and oxidizable gases in air or compressed air

• US 8,584,505 B2
• Filed: 01/05/2010
• Issued: 11/19/2013
• Est. Priority Date: 01/05/2009
• Status: Expired due to Fees

• Current Assignee: Synthesechemie Dr. Penth GmbH
• Original Assignee: Synthesechemie Dr. Penth GmbH
• Inventors: Penth, Bernd, Penth, Max, Penth, Felix
• Primary Examiner(s): Chang, Leonard
• Assistant Examiner(s): HULS, NATALIE F
• Application Number:
  US13/138,079
• Publication Number:
  US 20110265550A1
• Time in Patent Office: 1,414 Days
• Field of Search: 73/232, 73/233.2, 73/233.3, 73/28, 73/280.1, 73/290.1, 73 3101- 3103, 422/83, 422/93, 436139-143
• US Class Current: 73/23.2
• CPC Class Codes: G01N 27/66 and measuring current or voltage
• CPC Class Codes: G01N 33/0024 a chemical reaction taking place or a gas being eliminated in one or more channels
• CPC Class Codes: Y10T 436/218 Total hydrocarbon, flammability, combustibility [e.g., air-fuel mixture, etc.]

Abstract

The invention relates to a measuring instrument and method for detecting the content of oil, hydrocarbons and oxidizable gases in air or compressed air.

In order to develop a measuring instrument for detecting the content of oil, hydrocarbons and oxidizable gases in air or compressed air, said instrument being suitable for detecting concentrations in the lower μg/m³ range or in the ppb range and allowing measuring accuracy of 10 micrograms oil/m³ air at a measurement error in the single-digit percentage range, it is proposed according to the invention that the measuring instrument comprises an air or compressed-air connection and, connected thereto, a flow limiter to which a catalyst is connected that is connected in turn with a photoionization detector, switchable means being provided for routing the air or compressed air over the oxidation catalyst or past it directly to the photoionization detector.

Claims

1. A measuring instrument for detecting the content of oil, hydrocarbons and oxidizable gases in air or compressed air, wherein the measuring instrument has an air or compressed-air connection and, connected thereto, a flow limiter to which a thermal oxidation catalyst is connected that is connected in turn with a photoionization detector, switchable means being provided for routing the air or compressed air over the oxidation catalyst or past the oxidation catalyst directly to the photoionization detector, wherein a switchable test-gas inlet is fitted between the air or compressed-air connection and the flow limiter, and wherein the measuring instrument is configured to catalytically oxidize a variable proportion of the hydrocarbons and, in this way, generate dilution series for the purpose of carrying out a referencing measurement while hydrocarbon-containing air or compressed air is being analyzed.

2. The measuring instrument according to claim 1, wherein, in addition to the oxidation catalyst, at least one permeator for releasing a temporally constant, defined amount of hydrocarbon is installed, with switchable means being provided for routing the air or compressed air via the permeator or past the permeator directly to the photoionization detector.

3. The measuring instrument according to claim 1, wherein a switchable test-gas inlet is fitted between the air or compressed-air connection and the flow limiter.

4. The measuring instrument according to claim 1, wherein a switchable zero-air inlet is fitted between the air or compressed-air connection and the flow limiter.

5. The measuring instrument according to claim 1, wherein a switchable connection to an activated-charcoal tube is provided subsequent to the photoionization detector.

6. The measuring instrument according to claim 1, wherein an air-moisture compensator is fitted upstream of the photoionization detector.

7. A method for detecting the content of oil, hydrocarbons and oxidizable gases in air or compressed air using a measuring instrument having an air or compressed-air connection and, connected thereto, a flow limiter to which a thermal oxidation catalyst is connected that is connected in turn with a photoionization detector, switchable means being provided for routing the air or compressed air over the oxidation catalyst or past the oxidation catalyst directly to the photoionization detector, wherein a switchable test-gas inlet is fitted between the air or compressed-air connection and the flow limiter, and wherein, for the purpose of carrying out a referencing measurement while hydrocarbon-containing air or compressed air is being analyzed, a variable proportion of the hydrocarbons is catalytically oxidized and, in this way, dilution series are generated.

8. The method according to claim 7, wherein, for the purpose of carrying out a referencing measurement while hydrocarbon-containing air or compressed air is being analyzed, a variable proportion of zero air is mixed with the hydrocarbon-containing air and, in this way, dilution series are generated.

9. A method for detecting the content of oil, hydrocarbons and oxidizable gases in air or compressed air using a measuring instrument having an air or compressed-air connection and, connected thereto, a flow limiter to which a thermal oxidation catalyst is connected that is connected in turn with a photoionization detector, switchable means being provided for routing the air or compressed air over the oxidation catalyst or past the oxidation catalyst directly to the photoionization detector, wherein a switchable test-gas inlet is fitted between the air or compressed-air connection and the flow limiter, wherein an air-moisture compensator is fitted upstream of the photoionization detector, wherein, for the purpose of carrying out a referencing measurement while hydrocarbon-containing air or compressed air is being analyzed, a variable proportion of zero air is mixed with the hydrocarbon-containing air and, in this way, dilution series are generated, and wherein the zero air is catalytically treated and, in order to increase the measuring accuracy, both the hydrocarbon-containing air to be analyzed and the catalytically treated air or the zero air are enriched by way of a permeator with equal amounts of hydrocarbon so as to shift the measuring range into the linear measuring range.