Replacement of SCD Outer Pyrotube

Required devices

Parts name
Required number
Inner Pyrotube
PTFE Ferrule
Spanner, SCD, Maintenance
Spanner, SCD
Outer Pyrotube
O-ring, 4D P3
Installing JIG for Inner Pyrotube


Step 1

On the instrument monitor or workstation, check that the temperature of the column oven is lower than 40 °C, and check that the temperatures of the injection port and detector (SCD-IF part and electric furnace) are 50 °C or lower.
After checking the temperatures, turn OFF the main power to the instrument.

Step 2

Open the side cover.

Step 3

Remove the transfer line (★1).

While holding the transfer adapter (★2), loosen the transfer line (★1) and remove it.

Step 4

Remove the transfer adapter (★2) and inner pyrotube (①).

While holding the reductant inlet (★3) with a spanner, SCD (④), loosen the transfer adapter (★2) with a spanner, SCD, maintenance (③) and then remove the transfer adapter (★2) together with the inner pyrotube (①).


If you cannot remove the inner pyrotube with the transfer adapter, remove the inner pyrotube with tweezers.

Step 5

Loosen and remove the reductant inlet with a spanner, SCD (④).

Step 6

Remove the outer pyrotube (⑥) with tweezers (⑤).

Step 7

Install a new O-ring (⑦) on the outer pyrotube (⑥) for replacement.


Install the O-ring about 3 mm from the end.

Step 8

Insert the outer pyrotube (⑥) in the SCD.

Step 9

Ensure that the O-ring hits the back.

Check that it hits the back as shown in the following figure.


When the O-ring does not hit the back, the end of the outer pyrotube interferes with the parts inside the SCD as shown in the following figure.

In this case, turn the outer pyrotube several times while pushing it against the back.

Step 10

Install the reductant inlet.

Tighten it by hands and then additionally tighten it with a spanner, SCD (④).

Step 11

Detach the transfer adapter from the inner pyrotube.

Step 12

Detach the PTFE ferrule (②) from the transfer adapter (★2) and remove the back ring (★4).


Removed back ring will be used in the step 14.

Step 13

Install a new PTFE ferrule (②) on the inner pyrotube (①) for replacement.

Step 14

Install the back ring removed in the step 12 on the inner pyrotube.

Step 15

Install the transfer adapter on the inner pyrotube.

Step 16

Insert the inner pyrotube with the transfer adapter attached into the SCD.

Step 17

Temporarily tighten the transfer adapter (★2) to the extent that it moves back and forth while exposing the tip of inner pyrotube (①).

Step 18

Push the end face of the inner pyrotube (①) into the back with the jig (⑧) and fix to the transfer adapter (★2).


Tighten the transfer adapter (★2) and jig (⑧) until the gap between them is about 2mm.

Step 19

With the jig (⑧) still attached, fix the transfer adapter (★2) to the SCD using a spanner, SCD, maintenance (③) and a spanner, SCD (④).

Step 20

Remove the jig (⑧) from the transfer adapter (★2).

Step 21

Check that the end face of inner pyrotube does not protrude from the transfer adapter (★2).
If it is protruding, re-install the inner pyrotube.

Step 22

Additionally tighten the transfer adapter.

After tightening it by hand until it does not turn anymore, give additional tightening of half turn with a spanner, SCD, maintenance (③).

Step 23

Install the transfer line by hand-tight.

Step 24

Close the side cover.

Step 25

Turn on the main power of the instrument and start the GC.


After the SCD startup is completed, condition it for about 12 hours under the analysis conditions. After replacing the pyrotube, it takes time until the sensitivity is recovered.