A multi-block manifold facilitates assembly of the manifold in a fluid handling apparatus during manufacture and disassembly and removal of a secondary manifold block of the manifold during service without disconnecting external tubes and flow control devices from the manifold. The external tubes are isolated and integral to a primary manifold block of the manifold which is permanently mounted in the apparatus and the flow control devices are integral to the secondary manifold block which is quickly, releasably secured to the primary manifold block in the apparatus.