A manifold block for use in a portable positive pressure ventilator system comprising a ventilator for providing respiratory support to a patient, the manifold block comprising: a) three chambers that are formed within its interior, wherein: i) a first chamber comprises a diaphragm of a main inspiratory valve , which is a diaphragm valve, which works by activating the diaphragm to move up and down to cause opening and closing of a fluid passage ; ii) a second chamber is configured as an inspiratory valve first connector, which is a chamber into which gas from a source of pressurized air enters the manifold block ; and iii) a third chamber is configured as an inspiratory valve second connector, which is a chamber connected at a proximal end of the third chamber to a tubing system that leads to the patient; b) a wall that separates the second chamber from the third chamber ; c) a small diameter hole that passes through the wall; d) an outlet for an anti-asphyxia valve and all flow paths needed for fluidly connecting and operating components of the ventilator created within walls of the manifold block ; e) an opening leading from the first chamber into the second chamber , which is opened and closed by the diaphragm of the main inspiratory valve when the main inspiratory valve is activated by an inspiratory valve controller ; and the manifold block characterized in that , the small diameter hole that passes through the wall is configured to be a continuous bleed aperture . a) three chambers that are formed within its interior, wherein: i) a first chamber comprises a diaphragm of a main inspiratory valve , which is a diaphragm valve, which works by activating the diaphragm to move up and down to cause opening and closing of a fluid passage ; ii) a second chamber is configured as an inspiratory valve first connector, which is a chamber into which gas from a source of pressurized air enters the manifold block ; and iii) a third chamber is configured as an inspiratory valve second connector, which is a chamber connected at a proximal end of the third chamber to a tubing system that leads to the patient; i) a first chamber comprises a diaphragm of a main inspiratory valve , which is a diaphragm valve, which works by activating the diaphragm to move up and down to cause opening and closing of a fluid passage ; ii) a second chamber is configured as an inspiratory valve first connector, which is a chamber into which gas from a source of pressurized air enters the manifold block ; and iii) a third chamber is configured as an inspiratory valve second connector, which is a chamber connected at a proximal end of the third chamber to a tubing system that leads to the patient; b) a wall that separates the second chamber from the third chamber ; c) a small diameter hole that passes through the wall; d) an outlet for an anti-asphyxia valve and all flow paths needed for fluidly connecting and operating components of the ventilator created within walls of the manifold block ; e) an opening leading from the first chamber into the second chamber , which is opened and closed by the diaphragm of the main inspiratory valve when the main inspiratory valve is activated by an inspiratory valve controller ; and <EOS>