repair+tips

**Breakseal Crackers on IRMS:** 1) University of Ottawa system Explanation file for system in PDF form:
 * aGeneral:**
 * // **Angled breakseal cracker system for Manifold / Multiport--** // || // **Single breakseal cracker system for direct port entry** // ||

**Valves:** ** Needle Valves: ** W​hen adding a new needle valve, be sure to mount the valve WHILE the valve is in the open position. If in the closed position, the sealing piston will exhibit excessive force on the seal, resulting in a reduced pumping cross section. This will then result in detoriation of peak shapes or poor sensitivity.


 * SGE Valves:** Replacement on Thermo instruments:



Rotary Pumps: It is recommended to add a Foreline trap to the rotary pumps prior to the turbo and/or piranni gauge to protect them from oil migrating into the system.

Below are pictures of the mole sieve used in the Foreline trap. They can be reactivated or simply replaced during annual maintenace. The mole sieve is there to absorb oil mist from migrating into the ultra high vacuum part of the system (turbo pump to source). However, when new, the sieve does absorb atmospheric gases which causes the system to pump down slowly while the sieve degasses. The remedy to this is to simply put the sieve in a beaker and heat it at 100°C for 1 hour. Put the mole sieve back in the trap while still hot and start the vacuum system; vacuum will now be achieved quickly.

**Turbo pumps:**

The oil wick should be changed at least once a year. The picture below shows three stages of an oil wicks life: - New wick (Left): Oil on sponge is light in colour and clean. - Used wick (Center): One year old showing a yellowing of the oil and a greyish spot indicating the eventual failure of one or more of the turbos bearings. - Dead pump (Right): Complete collapse of the bearings and seal thus causing the pump to seize and needing a complete refurbishing.

Nafion drying tubes: __Nafion tubing__: Nafion tubing is available from [|PermaPure], but the size used in the Thermo drying tubes may be "special order". Nafion tubing can be cleaned, you can adapt their instructions for [|PD Cleaning]. You can use a pipette to push liquid through the center of the tube--but you must be careful not to tear it. Also, lay the tubing out straight when drying it, and try not to stretch it out too much when it is wet. It it recommended that you have backup nafion tubing on hand before starting the cleaning process in case the tubing tears during the cleaning process. Remember, the nafion tubing is "shrink-fitted" onto the capillary tubing in the Thermo drying tubes--they are not sealed by O-rings. To remove them, "wet" the end with methanol to swell the nafion and loosen it, then gently pull it off the capillary. Please note, it can be difficult to rethread the nafion through the drying tube. Try to push one capillary through the drying tube, slide on the nafion (after wetting with methanol), let it dry, then pull the nafion through attach to the capillary. You can use a junk piece of capillary tubing to do this, then connect the nafion to the devices capillary line. Becareful--it is easy to snap the capillary tubes and you may end up re-plumbing the whole system 
 * Drying tubes:**



Bellows: Thermo: replacement of potentiometer (belt driven blue thingamabob that tells computer position of bellows): Installing the ones Thermo used to use, the Bourns 3540s with the stainless steel collar, fixes problems. They run ~ $25 each from your favorite electronic supply store. 1. You'll need a soldering iron 2. remember to unplug the cable then melt the solder on the old potentiometer to remove the cable 3. do one at a time so you can look at the other one to make sure you've reconnected the cable correctly 4. remove the holder, take out old potentiometer and install new one--and transfer pulley, etc. 5. remount holder, solder in wires, plug back in 6. turn potentiometer to try to match bellows position (10 turn potentiometer, twist to hard stop, then turn back 5 turns to if bellows around 50% compression, i.e. guide pin in about half way along the slot) 7. put belt back on pulley 8. do hardware calibration--watch it, the guide pin should go almost the length of the slot, and go back to # 6 and try again if necessary (I tend to go from the wrong end, so it can take me a while)

High-Vacuum Gauge: Edwards D146-61-880. Inverted magnetron cold-cathode ionization gauge. For maintenance, cleaning, or schematic, see manual below.

Manual

Homemade Gas Bench Needles: There are several different designs available for home-made GasBench Needles (which can also be modified to create nice sparging needles for dissolved gas applications). Most designs follow McIlvin & Casciotti (2011) and antecedents.

Matthew R. McIlvin and Karen L. Casciotti. 2011. Technical Updates to the Bacterial Method for Nitrate Isotopic Analyses. Anal. Chem. 83: 1850-1856. doi 10.1021/ac1028984.

This design is for a side-hole needle sealed with epoxy: Low Cost GasBench Sampling Needle

This design uses a needle-in-a-needle design and does not require epoxy: