Is there a simple rule of thumb for time when pressure cooking?
As found on Chowhound:


  some "rule of thumb" are available but there are always exceptions!
  As usual things at high pressure cook three times faster - 
  The thing is, that the rules aren't always cut and dry. Chickpeas, for example, cook 90% faster in the pressure cooker (13 minutes instead of 2-3 hours). Your chicken stock, only 30-45 minutes at high pressure!
  These "rules" should be a starting point for figuring out the cooking time.
  Your main resource should be your own cooker's manual. It should include a good list of cooking times as they relate to your pressure cooker. The online chart that smtucker linked to is culled from pressure cooker manufacturer instructions books. There are other, more reliable versions online that have been updated with first-hand experience.
  For example, the chart in the link lists asparagus thick and thin pressure cooking time as the same - actually, you should ONLY pressure cook thick asparagus lest your expensive purchase of thin asparagus turn into soggy mush - a reputable timing chart will make this distinction.
  the given link can help you alot...
  http://www.hippressurecooking.com/p/p...