The calculated distance (air line) between Dayr Ḩāfir and As Safīrah is approximately 20 miles respectively 31 kilometers.
By car or train, the actual journey to As Safīrah is certainly longer, as only the direct route (as the crow flies) between Dayr Ḩāfir and As Safīrah has been calculated here.
Air line (approximately)
31 kilometers
17 nautical miles