We have an LPG dealership maybe this info will help:

All LPG you paid for should be 11kgs. meaning if the Tare Weight on the lpg cylinder for ex: 15.3 included dun yung weight ng tangke itself so be wary in buying pol valves lpg na mura na walang tare weight madalas di tama ang timbang nun a popular brand is m-gas pero tested sila sa tamang refill marami ng lumabas na brand any dealer can refill sa lpg plant as long as you have cylinders kaya nadadaya.

Unless you buy for Shellane or Petron Gasul my sarili silang regulator at talagang my Quality Control medyo mahal lang talaga because of the brand name advertising and so on..

for your safety always check for leaks sa tindahan palang o pagkadeliver before and after you install most common problem was the rubber touching dun sa regulator yung mga snap type shell and petron or caltex. sa pol valve naman is yun rubber ng regulator naiiwan sa valve kapag tinatangal.

Always check your rubber hose most of the time after 1 year malutong na yan. sa mahal ng lpg ngayon mabuti ng magtipid at mag ingat.