B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Type 3425
Aircraft Equipment Problem Less Severe
Flight Crew Diverted; Flight Crew FLC complied w / Automation / Advisory
Aircraft
Cruising at FL 400; my FO (First Officer) noticed a master caution flash of HYD. I immediately pulled up the HYD page and we saw that our System B quantity showed 0. We still had 3;000 PSI of pressure but that started to bleed down quickly eventually showing 0. We immediately went to the QRH and ran the checklist procedures for a Hydraulic system B failure. At our position we had the option of [two airports] for divert airports. We both agreed that ZZZ was our best option with it being a [company] hub and we would have plenty of support. We [advised ATC] and asked for priority handling. We contacted dispatch via ACARS and told them of our intentions. We coordinated with the flight attendants and told them of our situation; asking them to prepare the cabin for a landing with no expectations of an evacuation. I made a PA to the passengers informing them of our intentions and asked them to follow the instructions of the flight attendants. We received priority handling from ATC and center set us up for an extended downwind. We did a flaps 15 landing as required by the QRH configuring with the backup electric flap system. We had emergency trucks standing by as a precaution due to the emergency. We landed uneventfully and taxied to the gate unassisted. Everyone did a fantastic job. The mechanics met us right away; the gate agents took care of our passengers; a flight attendant supervisor met the airplane along with a rep from the chief pilot's office. An airplane was available and we were able to load our passengers and continue to [the original destination]. My FO did a fantastic job supporting me and the flight attendants did everything by the book with professionalism.  Our dispatcher was a huge help in coordinating our requests and getting us back into the air. I think the system worked and I was proud of [the company's] operation.
One quick master caution flash followed by HYD light; immediately checked system and quantity read zero. Pressure quickly dropped to zero. Diverted; ran checklist and landed uneventfully. Mechanic said a pinched O ring had given out and emptied the system. Spare airplane available at gate next door so we continued to [the original destination].
B737 Crew reported a Hydraulic system B failure with a diversion and uneventful landing.