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Balloon Fillers and Weights from the United Kingdom

Below are images of  Meteorological Office pilot-balloon filler sets Mark 8 and Mark VII.  These filler and weight sets are used as per the table below with hydrogen only.   No instructions or weights are included for ascents with helium.  The Mark 8 weight set below is for 10, 20 and 30 gram balloons.  The Mark VII set which has larger weights is for 100 gram balloons. The Mark 8 nozzle supports an ascent rate of 400ft/min with 10 gram balloons, 20 and 30 gram balloons will ascend at 500ft/min with nozzle and recommended weights.

 

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It should be noted that the Mark 8 set generates much lower free lifts than US standard sets do, even when taking in consideration the use of hydrogen gas.  The 10 gram Helium balloon US filler weighs 45 gm and the Mark 8 only 20 grams.   A US Army specification for a 40 gram filler shows an average ascent rate of 375ft/min (over 8 minutes) with Hydrogen yet the Mark 8 is supposed to generate an ascent rate of 400ft/min with a filler weight of only 20 grams.  

In the 30 gram hydrogen configuration the US filler weighs 125 grams and the Met Office Mark 8 weighs 71.5 grams.  The us ascent rate is 620ft/min (over 10 minutes) and the Met Office ascent specification is for 500ft/min with the Mark 8.

The Met Office fillers have a valve inside them attached to a wire loop that protrudes out of the bottom.  Since these fillers should be connected to a ground while inflating the procedures for both filler systems include slightly over filling the balloon, then unhooking the gas hose from the bottom of the filler and releasing the ground wire.  At that point the balloon is made neutrally buoyant by releasing some of the gas by pressing on the loop on the bottom of the filler. 

The Mark VII filler above is not in my collection.