A sprayer device with a trigger operated pump is operative for pumping and spraying liquid from an attached liquid container. The trigger sprayer includes valve body provided with a base portion that is configured to be mounted to the neck of the liquid container and a delivery nozzle from which the liquid is sprayed. A fluid flow path extends from the base portion to the delivery nozzle. A pumping chamber is in fluid communication with the flow passage and there is a vent opening between the pumping chamber and the interior of said base. A piston with spaced inboard and outboard seals is movable in the pumping chamber and the vent opening is located between the seals. A check valve is disposed between the vent opening and the interior of the base portion to prevent liquid from the container from backflowing into the pumping chamber during shipment and handling.