One aspect of the invention provides a component 112, 165 for a fluid dispenser 110 which defines a dosing chamber 120 for a piston member 114 to stroke in and has an end 160 adapted for engaging a fluid outlet 152 of the fluid dispenser or a seal 154 which overlies the fluid outlet 152 to selectively close and open the fluid outlet 152 or seal 154. Other aspects are disclosed herein.本發明之一態樣提供一種用於一流體分配器110之組件112、165，其界定一供一活塞構件114在其中衝擊之給藥腔室120且具有一經調適以嚙合該流體分配器之流體出口152或一覆蓋該流體出口152之密封件154以選擇性關閉及打開該流體出口152或密封件154之末端160。本文揭示其他態樣。
