public String toString() {
		return "valve1 = " + valve1 + " " + "valve2 = " + valve2 + " "
				+ "valve3 = " + valve3 + " " + "valve4 = " + valve4 + "\n"
				+ "i = " + i + " " + "f = " + f + " " + "source = " + source;
	}