The septum

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The injector is sealed from the air by a septum. This is a piece of silicone rubber, which prevents the GC system from leaking during sample introduction. The septum must be flexible, high temperature resistant and allow a large number of injections.

8. used and new septa

There are many different types of septa, each with their own properties. Septa are available in different sizes. The term 'durometer' is used to indicate the hardness of the silicone material. The lower the number, the softer the material.

Different Septa
Product	Max. temp (Celcius)	Color	Durometer	Low Bleed
Thermo Red	350	Red	50-55	Excellent
HT-X	350	Blue	50-60	Excellent
Hi-Temp White	250	White	40-45	Excellent
General Purpose Blue	250	Blue	40-45	Good
Hi-Temp Blue	300	Blue	55-60	Very good
W-type	250	Blue	55-60	Excellent
M-type	200	Green	50-55	Good
Hi-Temp Green	300	Green	55-60	Excellent
ULTRA SEP-R	350	Red	45-55	Excellent
W-10 Half Hole	250	Blue	50-55	Very good
F-138	250	Off White	25-35	Good
F-174N	250	Yellow/off white	25-35	Good