Find out how many prismatic springs or stainless scrubbers fit in your column. Choose a popular tube from the list or enter your own diameter and height – the calculator gives the volume, packing mass and number of packs to order.
Why is a column packed?
Packing creates a large surface in the column where the descending reflux meets the rising alcohol vapour. Each contact acts like a small distillation plate, so the better and more even the packing, the higher the strength and purity of the distillate.
Prismatic springs or scrubbers?
Stainless prismatic springs give the highest number of theoretical plates per metre and are the standard in reflux columns. Scrubbers are cheaper and have lower resistance, so they work well in pot/still columns, in the lower part of the column or as a support layer for the springs.
With the “share of springs” slider you can calculate mixed packing, e.g. 20% scrubbers at the bottom and 80% springs above.
How do I measure the column correctly?
What counts is the inner diameter: subtract two wall thicknesses from the outer diameter. Measure only the section to be packed – without the head and reflux condenser.
How we calculate
Column volume V = π × (d/2)² × h. Support scrubbers are pressed more tightly (about 400 g of scrubber per litre) and take up part of the volume, so we subtract it from the amount of springs. The weight is matched to the diameter: up to 30 mm – 20 g, 30–63 mm – 40 g, 63–80 mm – 60 g, above 80 mm – 100 g. Prismatic springs are measured by volume – you need as many litres of springs as the packed section of the column has. The suggested split is 15% copper springs (in the upper part of the column) and 85% stainless. For comparison we also show the number of scrubbers (about 270 g of scrubbers per litre of column). Packs are rounded up.
Frequently asked questions
How many prismatic springs fit in a 2" column?
A 50.8 × 1.5 mm tube has an inner diameter of about 47.8 mm, i.e. about 1.8 litres per metre of height – that is how many litres of springs you need per metre of column.
Should the springs be compacted?
No. Pour the springs in loosely and tap the column gently so they settle evenly. Compacting them increases pressure drop and the risk of flooding.
Why scrubbers at the bottom, middle and top of the column?
The bottom scrubber supports the springs so they do not fall into the boiler. The middle one splits the packing into two parts – the springs compact less and are easier to pour out for cleaning. The top one holds the packing down and stops small springs before the head.
How do I clean prismatic springs?
Pour the springs into a pot, cover with water and citric acid (about 2–3 tablespoons per litre) and boil for 20–30 minutes, then rinse thoroughly with clean water and dry. Without dismantling the column you can run water with citric acid through it and finish with clean water. Do not use chlorine-based cleaners – they damage stainless steel.
Do new springs need preparing before first use?
Yes. New springs may carry traces of manufacturing oil. Boil them in water with washing-up liquid or baking soda, rinse several times and dry. It is worth doing the first run with water or a cheap wash.
How much packing do I need for rectification and how much for a flavoured spirit?
For about 96% spirit, 1–1.5 m of springs is usually used. For flavoured spirits (fruit, grain) 0.3–0.8 m of packing is enough, as too many plates strip the aroma.
Should I add a reserve of springs?
By default the calculator uses the exact column volume. Springs settle slightly after the first runs and some get lost during cleaning – if you want something to top up with, choose a 5–10% reserve.
How often should springs be replaced or cleaned?
Stainless springs do not wear out. Rinse them after a few runs or boil them in a citric acid solution when they discolour.
Which springs for a 2" column?
For 2" columns (about 48–51 mm inside) 3 × 3 mm prismatic springs made of stainless wire are the most common choice.