How Does Gas Chromatography Work?

Hi,

This article was cited from http://www.explainthatstuff.com/chromatography.html at 30 Dec 2016. As long as surfed on the Internet, this link was very simple to describe about how gas chromatography work. 

Here's a very simplified overview of what happens in the gas chromatography process:

1. The eluant (carrier gas) is introduced from a gas cylinder outside the machine. It's called the carrier because that's exactly what it does—carry the sample we're studying through the machine. In gas chromatography, the carrier gas is the mobile phase.
2. The rate of flow of the carrier is carefully controlled to give the clearest separation of the components in the sample.
3. The carrier enters the machine through an inlet port/splitter.
4. The sample being measured is injected into the carrier gas using a syringe and instantly vaporizes (turns into gas form).
5. The gases that make up the sample separate out as they move along the column (orange), which is the stationary phase. The column is a very thin (capillary) tube, sometimes as much as 30–60m (100-200ft) long, coiled and entirely contained inside an oven (blue) that keeps it at a high enough temperature to ensure that the sample remains in gas form. The temperature of the oven can be carefully controlled.
6. As the sample separates out and its constituent gases travel along the column at different speeds, a detector senses and records them. Various different detectors can be used, including flame ionization detectors, thermal conductivity detectors, and mass spectrometers (usually separate machines).
7. The data analyzer/recorder attached to the machine draws a chromatogram (chart) with peaks corresponding to the relative amounts of the different chemicals in the sample.

That's all.

List of Standards and Codes Related to Grounding

Hi,

Here are list of standards and codes related to grounding, I made it as to remind:

API RP 540 page 36 to 38:
System grounding
"The following grounding practice is recommended:

1. System rated at less than or equal to 480 V that supply phase-to-neutral loads must be solidly grounded. These include 120/240-V, single-phase, three-wire systems; 208Y/120-V, three-phase, four-wire systems; and 480Y/277-V, three-phase, four-wire systems.
2. Low voltage (480-V and 600-V), three-wire systems should be either high-resistance grounded or solidly grounded.
3. All other plant distribution systems may be resistance grounded. These include 2,400 B through 34,500-V, three-phase, three-wire systems. (Open wire distribution may require solid grounding.)."

Equipment grounding
Structure and Process Equipment
"Steel building frameworks, switchgear structures, and similar installation should be grounded at several points (at least two point per structure) with substantial connection to the grounding system grid. Tanks, vessels, stacks, exchangers, and similar equipment not directly supported by or bolted to a grounded supporting structure should be grounded using a minimum of two connections to the grounding system grid...."

Motors and Generators
"Motor and generator enclosures should be connected to the overall plant grounding system..."

GPSA Engineering Data Book page 18-33:

"...Equipment grounding is separate from system grounding. Both are required to provide adequate protection."

If you know another which do not listed here. Do not hesitate to inform me.

That's all. 

Error Code: 1605 While Installing Microsoft SQL Server 2008 R2 Express Edition on Windows 7

Hi,

If you find a problem while installing Microsoft SQL Server 2008 R2 Express Edition (MSSQL) as follow:

Error Notification

Usually it is because the MSSQL been previously installed and you plan to do a re-installation. To solve this, here are steps should be performed:

1. Find first product code and reverse it. In may case is 4AB6A079 and reverse it and become 970A6BA4. Copy it.

2. Run regedit.exe.

3. Go to "Computer\HKEY_CLASSES_ROOT\Installer\UpgradeCodes".

4. Right click on "UpgradeCodes" and choose "Find..." menu.

5. Paste the code and click "Find Next" button.

Paste the code.

6. You will find the code then delete all folder containing the code (parent subkey).

After find key containing the code. Delete all parent folder.

7. Make sure you don't find the code again by push "F3".

8. Try to run MSSQL again. If you find another product code. Do previous steps.

In my case, I did 6 times to delete the folder containing code.

That's all.