GC-AED Site Preparation Guide

Background:

The following information has been assembled by Diablo Analytical, Inc. from several sources. Agilent Technologies provides instrument specification information. Other recommendations are a result of our experience with a wide range of customers. Diablo Analytical, Inc. provides this information at the request of GC-AED customers. The information is presented in good faith and is believed to be correct. However, Diablo Analytical, Inc. does not provide a warranty or assume any liability for the accuracy of this information or the results from utilization of this information by others.

Environmental Conditions:

Operating Temperature:	10 - 40 degrees C
Humidity	20-80%

Instrument Dimensions and Weight:

Work Surface	275cm wide by 78 cm deep by 120 cm above the surface
System Weight	Approximately 175 kg
Rear Clearance	25 cm from back of GC oven to other objects or structures

Power Requirements:

120 VAC systems	One 20-A circuit plus one or more 10-A circuits (dedicated)
OR for 220 VAC systems	One 15-A circuit plus one or more 10-A circuits

Gas Requirements:

Gas	Purity	Comment
Standard Gases (required for checkout):
Helium	99.9999%	Plasma Gas, 40-250 mL/min flows for the AED plus GC requirements
Helium (Optional)	99.999%	Plus a high quality gas purifier (e.g. a Valco Getter)
Hydrogen	99.997%	Plasma Reagent Gas, less than 10 mL/min for the AED
Oxygen	99.997%	Plasma Reagent Gas, less than 20 mL/min for the AED
10%CH4/N2	99.999%	Plasma Reagent Gas, used only for O-171, less than 10 mL/min for the AED
Nitrogen	99.99%	Spectrometer Purge Gas, 0.5 L/m for AED (configured for uninterrupted operation)
Optional Reagent Gas:
100% CH4	99.99%	Plasma Reagent Gas used only for N-388, less than 10 mL/min for the AED

The gas system should be designed to meet local regulations. The system includes gases that could present a safety concern if not designed and installed correctly. Safe and correct gas system implementation is the complete responsibility of the GC-AED customer.

GC-AED Gas System Components and Installation

The gas requirements for the GC-AED must be followed for successful operation. Diablo Analytical, Inc. has assisted many GC-AED customers and frequently their GC-AED gas systems are inadequate. As a result, Diablo Analytical, Inc. has worked with vendors to provide GC-AED gas system components that are designed for this use.

Gas Lines:

Diablo Analytical, Inc. recommends high quality stainless steel tubing. In some areas, electronic grade stainless steel tubing is available for a similar cost to other tubing. Some customers are successful with copper tubing, but this tubing performance is more variable. The GC-AED systems with the lowest background emission levels are generally installed with stainless steel. Always avoid house gas systems that have been installed in copper tubing. The presence of small leaks and contamination will affect the GC-AED performance. Few house gas systems work well unless they have been installed to strict specifications.

Lines from gas cylinders to lab Use ź" or larger tubing diameters (continuous)

Lines within lab to GC-AED Use 1/8" tubing diameters (continuous)

Connectors:

The Swagelok Ž type connectors with matching ferrules and tubing type are adequate.

Leak Checking:

The GC-AED is actually the best tool for identifying the presence of a leak in the system. However, a hand-held, high sensitivity, thermal conductivity detector (e.g. Leak Hunter Plus from Matheson Gas Products) is an excellent tool for locating leaks in the gas system. Small leaks can affect GC-AED performance.

Gas Cylinders:

The gases are generally available through your site gas supplier. However, watch the gas purity levels specified for the GC-AED.

Cylinder placement:

The location of gas cylinders is usually dictated by local regulations and safety policy. You will need to check on requirements in your location. However, it is best to minimize the distance that gas lines must travel. Cylinders are often located in the lab near the GC-AED, but this will depend on regulations and convenience. Cylinders and gas equipment located outdoors should be protected from weather.

Gas Regulators:

Gas regulators should be double-stage stainless steel diaphragm type construction. Some regulators are available in high-purity models that include all metal construction and are assembled without lubricating fluids.

Nitrogen Spectrometer Purge Gas:

A high-purity nitrogen generator (Whatman type) is recommended for spectrometer nitrogen. Other options include house nitrogen or vapor boil-off from liquid nitrogen dewars. Standard nitrogen cylinders do not provide sufficient operating time.

Helium Purification:

A high-quality heated purifier such as the "getter" unit produced by Valco Instruments is recommended to purify the helium.

Description	Model	Price
From Valco Instruments (800-367-8424, or 713-688-9345)
Valco Helium Gas Purifier (required) - 120 volt version	HT2	$750
220 volt option	HT2-220	$750