Why is the Pi-Pi urinal made from LLDPE rather than HDPE?

Question

Accepted Answer

LLDPE remains flexible and impact-resistant in frost down to −40 °C, which is more important than rigidity for a waterless urinal or sink in an unheated cabin. Both waterless urinals and plastic sinks Pi-Pi are made from the same material.

How LLDPE differs from HDPE

Both materials are polyethylene. HDPE is high-density polyethylene: it is stiffer and holds its shape better. LLDPE is linear low-density polyethylene: it is softer, more flexible, and better at absorbing impact. Where the product acts as a load-bearing part, stiffness is valuable. But a urinal or sink hangs on the wall of a cold room, gets bumped with tools, dropped during installation, and transported in a box. Therefore, flexibility is needed here: the plastic should bend, not crack.

What this means in winter in an unheated building

A garden shed, summer house, garage, or utility block freezes in winter. LLDPE does not crack in frost down to −40 °C: it retains flexibility and impact resistance, so an unheated room in winter is not a problem for the product. The material’s working range is from −40 °C to +60 °C, more about the lower and upper limits – in the answer about the temperature range.

Comparison with polypropylene is in a separate answer: LLDPE or PP.

Impacts, transportation, and installation

The material is only half the story. Pi-Pi products are made by rotational molding: resulting in a solid seamless wall 4–5 mm thick without welds and joints. No seam means no predetermined weak spot where a crack usually starts.

Urinals weigh 1.4–1.5 kg, sinks about 1.4 kg, so one person can hang them on the wall.
A plastic sink won’t break like ceramic and won’t rust like metal: it can be bumped with a tool or dropped during installation.
The smooth surface wipes clean quickly.

How to be sure yourself

If in doubt, it’s better to hold the product in your hands once. Business clients can order a sample on the samples page: this allows you to see the wall thickness, weight, and flexibility of the material before the main order. A private buyer can purchase the product with a regular order: the right to return the purchase within 14 days after receipt is retained.