Difference between revisions of "HMP155 Sensor Replacement"

Revision as of 10:26, 23 September 2022

Typically the HMP155 sensor head is encased in electrical tape. Cut it free first.
Once it's free you have a few strategies. I'll just outline them here and you can choose your own adventure it.

If there is a lot of other cable protection it might be difficult to pull the sensor head free of the radiation shield. In that case, use the small handled channel locks to gently (Gently!!) loosen the cable on the knurled metal bit. If you aren't careful the whole cable body might spin (or the side connected to the sensor head might) which is not what you want and leads to moisture intrusion and sensor failure.
- Once you've started the loosening with the channel locks, switch to finger removal as soon as practical.
with the cable removed you should be able to gently wiggle the HMP155 sensor head out of the housing. If it is stuck / difficult a few more twists may help.
Then, I like to photo the old and new HMP155 in succession to have for later the currently installed sensor.

Supser Site version: Radiation shield here is called an aspirated for the blower fan that sucks ambient air past the sensor head.

There is a PVC 90 degree elbow on the back end of the sensor. Be careful as this wants to launch off the tower.
For some cables there is a lot of slack and it is easy to navigate the swap. For others, minimal slack and you need to be extra conservative doing the change out.
First, remove the 90 degree elbow. For sensors with a bit of excess cable at this point you can slide the entire sensor out of the housing. Most have a bit of insulating foam around them to direct the air flow past the sensor and out the blower. Be careful not to let this blow away and fall to the ground.
With the sensor head removed, unscrew the sensor cable and in this process be careful not to lose the 90 degree elbow.
I like to photo the serial number of the old sensor on the tower at this point with background blurry but visible in the photos. This makes it easier to sort out later the elevation the sensor replacement took place at.
Then, photo the serial number of the new sensor.
swap. put the

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 * There is a PVC 90 degree elbow on the back end of the sensor.  Be careful as this wants to launch off the tower.
 * For some cables there is a lot of slack and it is easy to navigate the swap.  For others, minimal slack and you need to be extra conservative doing the change out.
-* First, remove the 90 degree elbow.  For sensors with a bit of excess cable at this point you can slide the entire sensor out of the housing.  Most have a bit of insulating foam around them to direct the air flow past the sensor and out the blower.  Be careful not to let this blow away.
+* First, remove the 90 degree elbow.  For sensors with a bit of excess cable at this point you can slide the entire sensor out of the housing.  Most have a bit of insulating foam around them to direct the air flow past the sensor and out the blower.  Be careful not to let this blow away and fall to the ground.
 * With the sensor head removed, unscrew the sensor cable and in this process be careful not to lose the 90 degree elbow.
 * I like to photo the serial number of the old sensor on the tower at this point with background blurry but visible in the photos. This makes it easier to sort out later the elevation the sensor replacement took place at.
 * Then, photo the serial number of the new sensor.
 * swap.  put the