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.
How much does it cost to install a propane 1 tank? Propane 1 tanks are most often used in domestic settings to supply appliances and household heating systems with the fuel required. The tanks come in a large array of sizes that can range from as little as 45 gallons and upwards of one thousand gallons.