private void pOMPAToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (pompa == null)
            {
                pompa = new Form_POMPA();

                pompa.FormClosed += new FormClosedEventHandler(formpompa);
                pompa.Show();
            }
            else
            {
                pompa.Activate();
            }
        }
 void formpompa(Object sender, FormClosedEventArgs e)
 {
     pompa = null;
 }