If you want to buy a gas chromatograph, if it can be used normally, in addition to the equipment necessary for conventional laboratories: such as: laboratory benches, glassware, gas sources, standard materials, etc., you need the following parts:
A source of gas
Second host
Three pillars
Four reference materials
5. Others (computers, printers, workstations, etc.)
So, how to buy these parts for users? In this and next newsletter, we will introduce how to make simple GC configuration for customers.
This time I will introduce you to the first two (selection of gas source and host)
A source of gas
The gas source of gas chromatography can be divided into four categories according to the purpose: carrier gas, fuel gas, auxiliary gas, driving gas.
Carrier gas: Through the entire analysis system, high purity and good quality are required. Generally speaking, we require customers to use large manufacturers and good brands of gas, and generally require the use of cylinder gas, it is best not to use a gas generator. Good carrier gas is the basis to ensure that the analysis can be carried out normally. Commonly used carrier gases are: nitrogen, hydrogen, argon, helium, etc.
Gas: hydrogen is generally used, as long as it can be ignited normally and does not interfere with the analysis. Users can use high-purity cylinder gas or hydrogen generators. If the budget is sufficient, it is better to use a hydrogen generator because it is safer.
Combustion gas: Air is generally used, as long as it can play the role of combustion, and it does not interfere with the analysis. Users can use high-purity cylinder gas or air generators.
Driving gas: generally air.
So when should we equip the gas?
When we allocate the gas source to the user, we generally consider it according to the detector:
FID: It needs to be equipped with carrier gas, fuel gas and auxiliary gas. Generally speaking, it is equipped with nitrogen (high-purity steel cylinder gas, 40L, with pressure reducing valve), hydrogen (cylinder gas or hydrogen generator), and air (cylinder gas or air source).
TCD: Carrier gas is required. In general, in order to improve the sensitivity, we recommend that the customer mix hydrogen (high-purity steel cylinder gas) or helium (high-purity steel cylinder gas). But if the customer wants to analyze hydrogen, we need to match argon or nitrogen or helium.
ECD: Carrier gas is required. Generally speaking, nitrogen (high-purity cylinder gas).
FPD: Same as FID.
TSD: Same as FID.
When the customer purchases an automatic valve, it needs to be equipped with driving gas. Generally speaking: air cylinder or air source can be used.
Second host
The host is mainly equipped with two parts for the user: sampling system and detection system.
Sampling system: As the name implies, the place where the sample enters is also the place used to vaporize the sample.
The following parts are commonly heard in the sampling system: (1) Capillary sample injector; (2) Fill sample injector; (3) Headspace sample injection; (4) Thermal analysis sample injection; (5) Valve injection kind.
Capillary injector: Generally speaking, a common gas chromatograph will have at least one capillary injector or filled injector. Therefore, when we configure for the customer, at least one sample injector (capillary or filling) is required. When the customer's analysis requires a capillary column: we equip the customer with a capillary injector; when the customer's analysis requires a packed column: we equip the customer with a packed injector. The instruments in our factory can be equipped with two capillary injectors or three filling injectors or filling / capillary injectors at the same time.
Fill sample injector: see capillary sample injector above.
Headspace sampling: Headspace sampling, thermal analysis, and valve sampling are usually gas sampling techniques. There is no conflict with the sample injector, we are based on the sample injector based on the customer's additional allocation. Headspace sampling is generally used for the determination of volatile components. In more than 90% of cases, the boiling point of the substance to be detected is below 120 degrees Celsius. The sample can be solid or liquid. Commonly used in: determination of ethanol in blood, determination of a volatile component in interior / car interior decoration materials, determination of various solvent residues, etc.
Thermal analysis sampling: generally used for the detection of certain components in the indoor / car air. Common analysis: TVOC.
Valve sampling: Six-port valve sampling, commonly used in gas sampling. If the customer's sample is gaseous and requires high precision, valve injection is often used.
Detection system: It is a system that converts the collected substances into electrical signals that can be seen on the computer. There are five types of detectors commonly used in gas chromatography. According to the substances that the customer needs to detect, we need to select the appropriate detector.
TCD: is a universal detector. It corresponds to all substances with different thermal conductivity of carrier gas, but its sensitivity is not high. Generally, it can only detect substances with a percentage content, and it cannot detect trace substances at the ppm or ppb level. Commonly used in the detection of permanent gas.
FID: Some people say it is a universal detector, and some people say it is a dedicated detector. Responsive to organic compounds, that is, C / H compounds. Weak response to compounds containing heteroatoms. In general, the detection at the ppm level can be achieved. It is a detector with very wide application at present.
ECD: Electronic capture detector. It is a special type detector. Extremely sensitive to electronegative substances. Generally used in the detection of compounds containing fluorochlorobromoiodine and other elements. Can achieve ppb level detection. Commonly used in the detection of organochlorine pesticide residues and chloroform and carbon tetrachloride.
FPD: is a dedicated detector. It has obvious response to sulfur and phosphorus compounds. The detection level is between ppm and ppb, and the sensitivity is average. Commonly used in the detection of organophosphorus pesticide residues and hydrogen sulfide and sulfur dioxide.
TSD: Also called NPD, nitrogen and phosphorus detector. It is a special type detector. It can detect compounds containing nitrogen and phosphorus. More sensitive, the detection level is between ppm and ppb. Not very commonly used. Maintenance is troublesome. (Organized by China Educational Equipment Purchasing Network)
The dining table and chair combination in a restaurant refers to the combination of tables and chairs used for dining. According to different needs and styles, restaurant dining table and chair combinations can be classified into various categories. The following will classify and introduce common dining table and chair combinations in restaurants.
1. Classified by purpose
1) Dinner table and chair combination: mainly used in formal dining venues, such as high-end restaurants, banquet halls, etc. The combination of dining tables and chairs usually uses high-end materials such as solid wood, marble, etc. The chairs are generally equipped with soft cushions to provide a comfortable dining experience.
2) Fast food table and chair combination: mainly used in fast food restaurants, coffee shops, and other fast-food restaurants. The combination of fast food tables and chairs usually adopts a simple and practical design. The tables are generally small, and the chairs are generally made of plastic or metal materials, which are easy to clean and move.
3) Outdoor table and chair combination: mainly used in outdoor dining venues, such as outdoor restaurants, balconies, etc. Outdoor table and chair combinations usually use materials with special treatments such as waterproof and anti-corrosion, such as aluminum alloy, plastic, etc., which have the characteristics of durability and easy cleaning.
2. Classify by Style
1) Modern style table and chair combinations: Modern style table and chair combinations usually adopt a simple and streamlined design, emphasizing practicality and comfort. The combination of modern style tables and chairs is suitable for modern restaurants, cafes, and other places.
2) European style table and chair combinations: European style table and chair combinations usually adopt gorgeous carved and curved designs, emphasizing details and decoration. The European style table and chair combination is suitable for high-end restaurants, banquet halls, and other places.
In summary, restaurant table and chair combinations are classified based on factors such as purpose and style. Different classifications are suitable for different types and needs of restaurants, and choosing the appropriate combination of dining tables and chairs can provide a better dining experience and comfort for the restaurant.
Beach table, beach chair,dining furniture
Foshan Shengshi Zhihui Technology Co., Ltd. , https://www.sshotelfurniture.com