Type   N1   N2
    43     121  455
    23     554  52
    85     74   615

dataf = pd.DataFrame()
for x in [df1,df2,...df20]:
    data = x.loc[x['Type']==23]
dataf.append(data)

N1   N2
    554  52
    153  87  and so on..

dfc = pd.concat([df1, df2])
dataf = dfc[dfc.Type == 23][['N1', 'N2']]