Christian Missions in Persia. Christianity was introduced in Persia in the Parthian period, and several bishoprics were established there (Latourette, II, pp. 263ff.).
You will likely pay more for the exchange, even if your tank is completely empty. An empty 20 lb tank will hold about 4.7 gallons of propane. That is $18.47 at $3.93 per gallon, which is the low quantity price (I just paid $3.44 per gallon when filling several tanks). The exchange is about the same price. Keep in mind this comparison is as if the exchange gives you a FULL tank.
Propane Tank Sizes. However you choose to use propane, Hopkins Propane can provide the proper tank size to fit your needs. Our service technicians are experienced with setting tanks from as small as 57 gallons (200lbs) up to 2400 gallons and larger to accommodate nearly any type of usage.